diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index 4c0f5075cf2b6..ba255b7844c88 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -46,6 +46,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Support/TypeSize.h"
+#include <optional>
 
 namespace llvm {
 
diff --git a/clang/include/clang/AST/ASTImporter.h b/clang/include/clang/AST/ASTImporter.h
index a6bb0e8aa9506..690ddceaec02d 100644
--- a/clang/include/clang/AST/ASTImporter.h
+++ b/clang/include/clang/AST/ASTImporter.h
@@ -29,6 +29,7 @@
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/AST/ASTImporterSharedState.h b/clang/include/clang/AST/ASTImporterSharedState.h
index 27f27a538bcb7..519ed27b6df09 100644
--- a/clang/include/clang/AST/ASTImporterSharedState.h
+++ b/clang/include/clang/AST/ASTImporterSharedState.h
@@ -18,6 +18,7 @@
 #include "clang/AST/ASTImporterLookupTable.h"
 #include "clang/AST/Decl.h"
 #include "llvm/ADT/DenseMap.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/AST/ASTStructuralEquivalence.h b/clang/include/clang/AST/ASTStructuralEquivalence.h
index 0b9e9e4e605fd..4550b50f398bf 100644
--- a/clang/include/clang/AST/ASTStructuralEquivalence.h
+++ b/clang/include/clang/AST/ASTStructuralEquivalence.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <queue>
 #include <utility>
 
diff --git a/clang/include/clang/AST/AbstractBasicReader.h b/clang/include/clang/AST/AbstractBasicReader.h
index bb589fb337b3e..ea28b4e24ed2e 100644
--- a/clang/include/clang/AST/AbstractBasicReader.h
+++ b/clang/include/clang/AST/AbstractBasicReader.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_AST_ABSTRACTBASICREADER_H
 
 #include "clang/AST/DeclTemplate.h"
+#include <optional>
 
 namespace clang {
 namespace serialization {
diff --git a/clang/include/clang/AST/AbstractBasicWriter.h b/clang/include/clang/AST/AbstractBasicWriter.h
index 41772ba0f63cd..6624a6e1640cc 100644
--- a/clang/include/clang/AST/AbstractBasicWriter.h
+++ b/clang/include/clang/AST/AbstractBasicWriter.h
@@ -11,6 +11,7 @@
 
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclTemplate.h"
+#include <optional>
 
 namespace clang {
 namespace serialization {
diff --git a/clang/include/clang/AST/ComparisonCategories.h b/clang/include/clang/AST/ComparisonCategories.h
index 7b73b582fe2a6..aac8124370d6f 100644
--- a/clang/include/clang/AST/ComparisonCategories.h
+++ b/clang/include/clang/AST/ComparisonCategories.h
@@ -19,6 +19,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include <array>
 #include <cassert>
+#include <optional>
 #include <vector>
 
 namespace llvm {
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index e9719fd7d51ef..388cb517b537a 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -46,6 +46,7 @@
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index b7032d00d9887..085bd2e395118 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -39,6 +39,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <iterator>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index ed76cfaa4e56a..2a81b46a05413 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -36,6 +36,7 @@
 #include "llvm/Support/AtomicOrdering.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/TrailingObjects.h"
+#include <optional>
 
 namespace clang {
   class APValue;
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index b7543251aa9d4..3851d74b1d69e 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -51,6 +51,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <memory>
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/AST/ExprObjC.h b/clang/include/clang/AST/ExprObjC.h
index 0c0629cd00c68..f1d21608af095 100644
--- a/clang/include/clang/AST/ExprObjC.h
+++ b/clang/include/clang/AST/ExprObjC.h
@@ -40,6 +40,7 @@
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/AST/ExternalASTSource.h b/clang/include/clang/AST/ExternalASTSource.h
index b1851afcda37c..18f981673ed50 100644
--- a/clang/include/clang/AST/ExternalASTSource.h
+++ b/clang/include/clang/AST/ExternalASTSource.h
@@ -30,6 +30,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <iterator>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/AST/FormatString.h b/clang/include/clang/AST/FormatString.h
index a2b8122890b92..e1f8a2d2798c2 100644
--- a/clang/include/clang/AST/FormatString.h
+++ b/clang/include/clang/AST/FormatString.h
@@ -19,6 +19,7 @@
 #define LLVM_CLANG_AST_FORMATSTRING_H
 
 #include "clang/AST/CanonicalType.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/AST/Mangle.h b/clang/include/clang/AST/Mangle.h
index 80e7a9df01b55..2ed2d76fdcd72 100644
--- a/clang/include/clang/AST/Mangle.h
+++ b/clang/include/clang/AST/Mangle.h
@@ -19,6 +19,7 @@
 #include "clang/Basic/ABI.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/Support/Casting.h"
+#include <optional>
 
 namespace llvm {
   class raw_ostream;
diff --git a/clang/include/clang/AST/NSAPI.h b/clang/include/clang/AST/NSAPI.h
index a8bd2d0f17e6f..7692502355f02 100644
--- a/clang/include/clang/AST/NSAPI.h
+++ b/clang/include/clang/AST/NSAPI.h
@@ -12,6 +12,7 @@
 #include "clang/Basic/IdentifierTable.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 namespace clang {
   class ASTContext;
diff --git a/clang/include/clang/AST/Stmt.h b/clang/include/clang/AST/Stmt.h
index e4a6ec975f2b0..1f7b09590f8aa 100644
--- a/clang/include/clang/AST/Stmt.h
+++ b/clang/include/clang/AST/Stmt.h
@@ -36,6 +36,7 @@
 #include <cassert>
 #include <cstddef>
 #include <iterator>
+#include <optional>
 #include <string>
 
 namespace llvm {
diff --git a/clang/include/clang/AST/TemplateBase.h b/clang/include/clang/AST/TemplateBase.h
index 6ba867d43a988..d4bf4e35a54f9 100644
--- a/clang/include/clang/AST/TemplateBase.h
+++ b/clang/include/clang/AST/TemplateBase.h
@@ -30,6 +30,7 @@
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <optional>
 
 namespace llvm {
 
diff --git a/clang/include/clang/AST/TemplateName.h b/clang/include/clang/AST/TemplateName.h
index d723356767ddc..c7489f637fe8f 100644
--- a/clang/include/clang/AST/TemplateName.h
+++ b/clang/include/clang/AST/TemplateName.h
@@ -21,6 +21,7 @@
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
 #include <cassert>
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index 25d4cab598049..21843c3cc59ed 100644
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -50,6 +50,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
+#include <optional>
 #include <string>
 #include <type_traits>
 #include <utility>
diff --git a/clang/include/clang/ASTMatchers/ASTMatchFinder.h b/clang/include/clang/ASTMatchers/ASTMatchFinder.h
index 9a1aad656fbef..9ff3012546885 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchFinder.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchFinder.h
@@ -44,6 +44,7 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/Timer.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/ASTMatchers/ASTMatchers.h b/clang/include/clang/ASTMatchers/ASTMatchers.h
index f1b858c511c03..7dda0806b9d20 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchers.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -90,6 +90,7 @@
 #include <cstddef>
 #include <iterator>
 #include <limits>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/ASTMatchers/ASTMatchersInternal.h b/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
index 04213dcf48083..82529825622de 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
@@ -66,6 +66,7 @@
 #include <cstdint>
 #include <map>
 #include <memory>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <type_traits>
diff --git a/clang/include/clang/ASTMatchers/Dynamic/Parser.h b/clang/include/clang/ASTMatchers/Dynamic/Parser.h
index 26e321c98ff6a..ebe85978b9df5 100644
--- a/clang/include/clang/ASTMatchers/Dynamic/Parser.h
+++ b/clang/include/clang/ASTMatchers/Dynamic/Parser.h
@@ -42,6 +42,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/include/clang/ASTMatchers/Dynamic/Registry.h b/clang/include/clang/ASTMatchers/Dynamic/Registry.h
index ee47469c6e182..e33e0c7857a84 100644
--- a/clang/include/clang/ASTMatchers/Dynamic/Registry.h
+++ b/clang/include/clang/ASTMatchers/Dynamic/Registry.h
@@ -21,6 +21,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/ASTMatchers/Dynamic/VariantValue.h b/clang/include/clang/ASTMatchers/Dynamic/VariantValue.h
index eec9255134de6..d67d5c3c8307f 100644
--- a/clang/include/clang/ASTMatchers/Dynamic/VariantValue.h
+++ b/clang/include/clang/ASTMatchers/Dynamic/VariantValue.h
@@ -22,6 +22,7 @@
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/Optional.h"
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h b/clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h
index 6bb99f0db7b85..9c34f335386f1 100644
--- a/clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h
+++ b/clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h
@@ -59,6 +59,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <iterator>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/Analysis/AnyCall.h b/clang/include/clang/Analysis/AnyCall.h
index d18c04648bda0..801105b85929a 100644
--- a/clang/include/clang/Analysis/AnyCall.h
+++ b/clang/include/clang/Analysis/AnyCall.h
@@ -16,6 +16,7 @@
 #include "clang/AST/Decl.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprObjC.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Analysis/BodyFarm.h b/clang/include/clang/Analysis/BodyFarm.h
index d947ac0702091..f6ed9d645973d 100644
--- a/clang/include/clang/Analysis/BodyFarm.h
+++ b/clang/include/clang/Analysis/BodyFarm.h
@@ -18,6 +18,7 @@
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Analysis/CFG.h b/clang/include/clang/Analysis/CFG.h
index c3721d06e9eaa..f2cf9f96ed8b2 100644
--- a/clang/include/clang/Analysis/CFG.h
+++ b/clang/include/clang/Analysis/CFG.h
@@ -31,6 +31,7 @@
 #include <cstddef>
 #include <iterator>
 #include <memory>
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h
index 62ab9899206b8..03d48caf9b09b 100644
--- a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h
+++ b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h
@@ -15,6 +15,7 @@
 #define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_DATAFLOWANALYSIS_H
 
 #include <iterator>
+#include <optional>
 #include <type_traits>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h
index 72ddfbb780f17..4ab1e9cb889c0 100644
--- a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h
+++ b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h
@@ -27,6 +27,7 @@
 #include "llvm/Support/Compiler.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <type_traits>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/Analysis/FlowSensitive/Solver.h b/clang/include/clang/Analysis/FlowSensitive/Solver.h
index 93568b1197933..d0f954d673aba 100644
--- a/clang/include/clang/Analysis/FlowSensitive/Solver.h
+++ b/clang/include/clang/Analysis/FlowSensitive/Solver.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 namespace clang {
 namespace dataflow {
diff --git a/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h b/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h
index 05e958c2d40c3..ab04a704d1f9e 100644
--- a/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h
+++ b/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h
@@ -14,6 +14,7 @@
 #ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_TYPEERASEDDATAFLOWANALYSIS_H
 #define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_TYPEERASEDDATAFLOWANALYSIS_H
 
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/include/clang/Analysis/MacroExpansionContext.h b/clang/include/clang/Analysis/MacroExpansionContext.h
index ea9ced02c6139..bfa529f601281 100644
--- a/clang/include/clang/Analysis/MacroExpansionContext.h
+++ b/clang/include/clang/Analysis/MacroExpansionContext.h
@@ -16,6 +16,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Analysis/PathDiagnostic.h b/clang/include/clang/Analysis/PathDiagnostic.h
index 342053a7c3c89..e6c7173d6c158 100644
--- a/clang/include/clang/Analysis/PathDiagnostic.h
+++ b/clang/include/clang/Analysis/PathDiagnostic.h
@@ -30,6 +30,7 @@
 #include <list>
 #include <map>
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 #include <utility>
diff --git a/clang/include/clang/Analysis/ProgramPoint.h b/clang/include/clang/Analysis/ProgramPoint.h
index 1df5b74b20a36..2478137663ca7 100644
--- a/clang/include/clang/Analysis/ProgramPoint.h
+++ b/clang/include/clang/Analysis/ProgramPoint.h
@@ -24,6 +24,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/DataTypes.h"
 #include <cassert>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/Analysis/RetainSummaryManager.h b/clang/include/clang/Analysis/RetainSummaryManager.h
index 3171dc314c643..58129df843802 100644
--- a/clang/include/clang/Analysis/RetainSummaryManager.h
+++ b/clang/include/clang/Analysis/RetainSummaryManager.h
@@ -25,6 +25,7 @@
 #include "clang/Analysis/AnyCall.h"
 #include "clang/Analysis/SelectorExtras.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/include/clang/Basic/DarwinSDKInfo.h b/clang/include/clang/Basic/DarwinSDKInfo.h
index 6a13ddd9d522e..7a441871e77e5 100644
--- a/clang/include/clang/Basic/DarwinSDKInfo.h
+++ b/clang/include/clang/Basic/DarwinSDKInfo.h
@@ -15,6 +15,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include <optional>
 
 namespace llvm {
 namespace json {
diff --git a/clang/include/clang/Basic/Diagnostic.h b/clang/include/clang/Basic/Diagnostic.h
index 927ed14347a00..9b5272e283106 100644
--- a/clang/include/clang/Basic/Diagnostic.h
+++ b/clang/include/clang/Basic/Diagnostic.h
@@ -32,6 +32,7 @@
 #include <list>
 #include <map>
 #include <memory>
+#include <optional>
 #include <string>
 #include <type_traits>
 #include <utility>
diff --git a/clang/include/clang/Basic/DiagnosticError.h b/clang/include/clang/Basic/DiagnosticError.h
index 76d893a5ccf8e..a42329bbd8a53 100644
--- a/clang/include/clang/Basic/DiagnosticError.h
+++ b/clang/include/clang/Basic/DiagnosticError.h
@@ -11,6 +11,7 @@
 
 #include "clang/Basic/PartialDiagnostic.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Basic/DiagnosticIDs.h b/clang/include/clang/Basic/DiagnosticIDs.h
index 91b180f8004de..3211dba160eca 100644
--- a/clang/include/clang/Basic/DiagnosticIDs.h
+++ b/clang/include/clang/Basic/DiagnosticIDs.h
@@ -17,6 +17,7 @@
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/StringRef.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang/include/clang/Basic/DirectoryEntry.h b/clang/include/clang/Basic/DirectoryEntry.h
index dca68ef1b43d5..6c8da1213655a 100644
--- a/clang/include/clang/Basic/DirectoryEntry.h
+++ b/clang/include/clang/Basic/DirectoryEntry.h
@@ -23,6 +23,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/ErrorOr.h"
 
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/Basic/FileEntry.h b/clang/include/clang/Basic/FileEntry.h
index 6ff9c19a7921d..93e84cf233a30 100644
--- a/clang/include/clang/Basic/FileEntry.h
+++ b/clang/include/clang/Basic/FileEntry.h
@@ -25,6 +25,7 @@
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem/UniqueID.h"
 
+#include <optional>
 #include <utility>
 
 namespace llvm {
diff --git a/clang/include/clang/Basic/FileSystemStatCache.h b/clang/include/clang/Basic/FileSystemStatCache.h
index d37f2d507f836..e9f9fa31a0b3a 100644
--- a/clang/include/clang/Basic/FileSystemStatCache.h
+++ b/clang/include/clang/Basic/FileSystemStatCache.h
@@ -23,6 +23,7 @@
 #include <cstdint>
 #include <ctime>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index 41b0426a2d4b8..47d04f3a3c112 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/FloatingPointMode.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Triple.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang/include/clang/Basic/Module.h b/clang/include/clang/Basic/Module.h
index 11c021eb6e58c..cb430d5f8925d 100644
--- a/clang/include/clang/Basic/Module.h
+++ b/clang/include/clang/Basic/Module.h
@@ -33,6 +33,7 @@
 #include <cstdint>
 #include <ctime>
 #include <iterator>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/Basic/ProfileList.h b/clang/include/clang/Basic/ProfileList.h
index f7768004b23b0..23829bd466f4f 100644
--- a/clang/include/clang/Basic/ProfileList.h
+++ b/clang/include/clang/Basic/ProfileList.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Basic/Sarif.h b/clang/include/clang/Basic/Sarif.h
index d76b9d1567cc0..9fbe70ef51947 100644
--- a/clang/include/clang/Basic/Sarif.h
+++ b/clang/include/clang/Basic/Sarif.h
@@ -43,6 +43,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <initializer_list>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
index d7f81255e6119..27c8fe86e3268 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/include/clang/Basic/SourceManager.h
@@ -53,6 +53,7 @@
 #include <cstddef>
 #include <map>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/CrossTU/CrossTranslationUnit.h b/clang/include/clang/CrossTU/CrossTranslationUnit.h
index 47b48ce06c3af..5002c1c23e79a 100644
--- a/clang/include/clang/CrossTU/CrossTranslationUnit.h
+++ b/clang/include/clang/CrossTU/CrossTranslationUnit.h
@@ -23,6 +23,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 class CompilerInstance;
diff --git a/clang/include/clang/ExtractAPI/Serialization/SymbolGraphSerializer.h b/clang/include/clang/ExtractAPI/Serialization/SymbolGraphSerializer.h
index 9bf6083fe901e..e6c18660e0118 100644
--- a/clang/include/clang/ExtractAPI/Serialization/SymbolGraphSerializer.h
+++ b/clang/include/clang/ExtractAPI/Serialization/SymbolGraphSerializer.h
@@ -24,6 +24,7 @@
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 namespace clang {
 namespace extractapi {
diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
index 36472c65a8928..c5bfbfe87f5e4 100644
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/SourceMgr.h"
+#include <optional>
 #include <system_error>
 
 namespace llvm {
diff --git a/clang/include/clang/Frontend/ASTUnit.h b/clang/include/clang/Frontend/ASTUnit.h
index c87e143b9cf45..62c0190e77d89 100644
--- a/clang/include/clang/Frontend/ASTUnit.h
+++ b/clang/include/clang/Frontend/ASTUnit.h
@@ -41,6 +41,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/Frontend/CommandLineSourceLoc.h b/clang/include/clang/Frontend/CommandLineSourceLoc.h
index f5114758e70a8..4637a1cc74111 100644
--- a/clang/include/clang/Frontend/CommandLineSourceLoc.h
+++ b/clang/include/clang/Frontend/CommandLineSourceLoc.h
@@ -17,6 +17,7 @@
 #include "clang/Basic/LLVM.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Frontend/CompilerInstance.h b/clang/include/clang/Frontend/CompilerInstance.h
index 577daad86b204..04d32c241d9da 100644
--- a/clang/include/clang/Frontend/CompilerInstance.h
+++ b/clang/include/clang/Frontend/CompilerInstance.h
@@ -26,6 +26,7 @@
 #include <cassert>
 #include <list>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/Frontend/FrontendOptions.h b/clang/include/clang/Frontend/FrontendOptions.h
index 9183fcb99fe9f..a757749ba0097 100644
--- a/clang/include/clang/Frontend/FrontendOptions.h
+++ b/clang/include/clang/Frontend/FrontendOptions.h
@@ -19,6 +19,7 @@
 #include <cassert>
 #include <map>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang/include/clang/Lex/HeaderMap.h b/clang/include/clang/Lex/HeaderMap.h
index 2a4af28eaef0c..9836765403a0a 100644
--- a/clang/include/clang/Lex/HeaderMap.h
+++ b/clang/include/clang/Lex/HeaderMap.h
@@ -21,6 +21,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Lex/Lexer.h b/clang/include/clang/Lex/Lexer.h
index 35c6a7bdd5cae..3e21987107f64 100644
--- a/clang/include/clang/Lex/Lexer.h
+++ b/clang/include/clang/Lex/Lexer.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <cassert>
 #include <cstdint>
+#include <optional>
 #include <string>
 
 namespace llvm {
diff --git a/clang/include/clang/Lex/ModuleMap.h b/clang/include/clang/Lex/ModuleMap.h
index ba7b6813c6141..2ce596110bbce 100644
--- a/clang/include/clang/Lex/ModuleMap.h
+++ b/clang/include/clang/Lex/ModuleMap.h
@@ -30,6 +30,7 @@
 #include "llvm/ADT/Twine.h"
 #include <ctime>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/Lex/PreprocessingRecord.h b/clang/include/clang/Lex/PreprocessingRecord.h
index c385bc6a73179..fd269fd2e9bb6 100644
--- a/clang/include/clang/Lex/PreprocessingRecord.h
+++ b/clang/include/clang/Lex/PreprocessingRecord.h
@@ -29,6 +29,7 @@
 #include <cassert>
 #include <cstddef>
 #include <iterator>
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index b39eca9e7983e..afef702df865c 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -51,6 +51,7 @@
 #include <cstdint>
 #include <map>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/Lex/PreprocessorOptions.h b/clang/include/clang/Lex/PreprocessorOptions.h
index d51f2bcbe14ed..8ad2cc23fa5ba 100644
--- a/clang/include/clang/Lex/PreprocessorOptions.h
+++ b/clang/include/clang/Lex/PreprocessorOptions.h
@@ -18,6 +18,7 @@
 #include <functional>
 #include <map>
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 #include <utility>
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index 8d934d59a580b..4f87d55b19dc0 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -28,6 +28,7 @@
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include <memory>
+#include <optional>
 #include <stack>
 
 namespace clang {
diff --git a/clang/include/clang/Sema/CodeCompleteConsumer.h b/clang/include/clang/Sema/CodeCompleteConsumer.h
index 814201a02dcc8..063c96049e385 100644
--- a/clang/include/clang/Sema/CodeCompleteConsumer.h
+++ b/clang/include/clang/Sema/CodeCompleteConsumer.h
@@ -29,6 +29,7 @@
 #include "llvm/Support/type_traits.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/Sema/Lookup.h b/clang/include/clang/Sema/Lookup.h
index 8b11273416c55..34a875699e7bf 100644
--- a/clang/include/clang/Sema/Lookup.h
+++ b/clang/include/clang/Sema/Lookup.h
@@ -30,6 +30,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Casting.h"
 #include <cassert>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/Sema/Scope.h b/clang/include/clang/Sema/Scope.h
index caeef066e9e94..72908793db891 100644
--- a/clang/include/clang/Sema/Scope.h
+++ b/clang/include/clang/Sema/Scope.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/iterator_range.h"
 #include <cassert>
+#include <optional>
 
 namespace llvm {
 
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index be5265b7968b8..33d8ed6aa3519 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -68,6 +68,7 @@
 #include "llvm/Frontend/OpenMP/OMPConstants.h"
 #include <deque>
 #include <memory>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <vector>
diff --git a/clang/include/clang/Sema/SemaConcept.h b/clang/include/clang/Sema/SemaConcept.h
index a5b65f2edf940..1cbe18fb2a356 100644
--- a/clang/include/clang/Sema/SemaConcept.h
+++ b/clang/include/clang/Sema/SemaConcept.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/Sema/SemaLambda.h b/clang/include/clang/Sema/SemaLambda.h
index 494568722d9f7..fcc4ebee7cebd 100644
--- a/clang/include/clang/Sema/SemaLambda.h
+++ b/clang/include/clang/Sema/SemaLambda.h
@@ -16,6 +16,7 @@
 #define LLVM_CLANG_SEMA_SEMALAMBDA_H
 
 #include "clang/AST/ASTLambda.h"
+#include <optional>
 
 namespace clang {
 namespace sema {
diff --git a/clang/include/clang/Sema/Template.h b/clang/include/clang/Sema/Template.h
index 8f3657d19aafc..52fff8e9515a2 100644
--- a/clang/include/clang/Sema/Template.h
+++ b/clang/include/clang/Sema/Template.h
@@ -23,6 +23,7 @@
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SmallVector.h"
 #include <cassert>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/Sema/TemplateDeduction.h b/clang/include/clang/Sema/TemplateDeduction.h
index ba35a5a744959..e8d235c69e357 100644
--- a/clang/include/clang/Sema/TemplateDeduction.h
+++ b/clang/include/clang/Sema/TemplateDeduction.h
@@ -26,6 +26,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include <cassert>
 #include <cstddef>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index 1b9b12cc5c9c2..f2a7f265d6f65 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -57,6 +57,7 @@
 #include <ctime>
 #include <deque>
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 #include <utility>
diff --git a/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h b/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h
index 78bc46763b4c4..d89eaf50da68a 100644
--- a/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h
+++ b/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h
@@ -38,6 +38,7 @@
 #include "llvm/ADT/iterator_range.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitors.h b/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitors.h
index 48da56c00f7a3..6ccae6fd06785 100644
--- a/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitors.h
+++ b/clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitors.h
@@ -25,6 +25,7 @@
 #include "llvm/ADT/StringRef.h"
 #include <list>
 #include <memory>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h
index 091c3ce20e717..360f81e1dc154 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h
@@ -19,6 +19,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/Compiler.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h
index 7394a7d32eafb..6ac768c6e8201 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h
@@ -45,6 +45,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
 #include <limits>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h
index a40d883a15ecf..ce1407e68630c 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h
@@ -16,6 +16,7 @@
 
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
+#include <optional>
 
 namespace clang {
 namespace ento {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h
index f7a39e71f1b2a..2ad5e1f81078a 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h
@@ -17,6 +17,7 @@
 #include "clang/AST/Stmt.h"
 #include "clang/Basic/OperatorKinds.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <tuple>
 
 namespace clang {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h
index 92df266115243..eb845066db507 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include <memory>
+#include <optional>
 #include <utility>
 
 namespace llvm {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h
index faabd48574bd2..5b7e337c1bc66 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h
@@ -38,6 +38,7 @@
 #include <cassert>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h
index dd1b75559f3a3..a5e075c564696 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h
@@ -36,6 +36,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/WorkList.h"
 #include "llvm/ADT/ArrayRef.h"
 #include <cassert>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h
index 5359fea43d34b..effe9e4c237fc 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h
@@ -21,6 +21,7 @@
 #include "llvm/ADT/SmallBitVector.h"
 #include <cassert>
 #include <deque>
+#include <optional>
 #include <utility>
 
 namespace clang {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
index aa21ef272f202..74551122e35a5 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
@@ -37,6 +37,7 @@
 #include <cassert>
 #include <cstdint>
 #include <limits>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h
index cdb6d8f82cf88..0e37182ff77ad 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h
@@ -23,6 +23,7 @@
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/ImmutableMap.h"
 #include "llvm/Support/Allocator.h"
+#include <optional>
 #include <utility>
 
 namespace llvm {
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h
index 7bbb4c6b1444e..d00432dbf22d3 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConstraintManager.h
@@ -18,6 +18,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/RangedConstraintManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SMTConv.h"
+#include <optional>
 
 typedef llvm::ImmutableSet<
     std::pair<clang::ento::SymbolRef, const llvm::SMTExpr *>>
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h
index adc3af9e775b9..298435fcda6f6 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h
@@ -30,6 +30,7 @@
 #include "llvm/ADT/ImmutableList.h"
 #include "llvm/ADT/Optional.h"
 #include <cstdint>
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
index 328d9501da844..2e4afb29ff843 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
@@ -25,6 +25,7 @@
 #include "llvm/Support/Casting.h"
 #include <cassert>
 #include <cstdint>
+#include <optional>
 #include <utility>
 
 //==------------------------------------------------------------------------==//
diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h
index 80db6bf5667e4..bf2dfd1b96721 100644
--- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h
+++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h
@@ -28,6 +28,7 @@
 #include <cassert>
 #include <cstdint>
 #include <memory>
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/include/clang/Tooling/ASTDiff/ASTDiff.h b/clang/include/clang/Tooling/ASTDiff/ASTDiff.h
index 5fe6db6cb133b..a84444a082294 100644
--- a/clang/include/clang/Tooling/ASTDiff/ASTDiff.h
+++ b/clang/include/clang/Tooling/ASTDiff/ASTDiff.h
@@ -20,6 +20,7 @@
 #define LLVM_CLANG_TOOLING_ASTDIFF_ASTDIFF_H
 
 #include "clang/Tooling/ASTDiff/ASTDiffInternal.h"
+#include <optional>
 
 namespace clang {
 namespace diff {
diff --git a/clang/include/clang/Tooling/AllTUsExecution.h b/clang/include/clang/Tooling/AllTUsExecution.h
index 43f2792457e71..fcc952fe80e48 100644
--- a/clang/include/clang/Tooling/AllTUsExecution.h
+++ b/clang/include/clang/Tooling/AllTUsExecution.h
@@ -16,6 +16,7 @@
 
 #include "clang/Tooling/ArgumentsAdjusters.h"
 #include "clang/Tooling/Execution.h"
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/include/clang/Tooling/Core/Replacement.h b/clang/include/clang/Tooling/Core/Replacement.h
index 2c4fb8f53c1e2..929d61971e557 100644
--- a/clang/include/clang/Tooling/Core/Replacement.h
+++ b/clang/include/clang/Tooling/Core/Replacement.h
@@ -26,6 +26,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_ostream.h"
 #include <map>
+#include <optional>
 #include <set>
 #include <string>
 #include <system_error>
diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
index 8f820f235f485..510c41f51c323 100644
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
@@ -17,6 +17,7 @@
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <mutex>
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningTool.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningTool.h
index f191ea1822837..7262ac8eefa22 100644
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningTool.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningTool.h
@@ -16,6 +16,7 @@
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/StringMap.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h
index 36ac2e3fbff78..71638935b5f13 100644
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h
@@ -17,6 +17,7 @@
 #include "clang/Tooling/DependencyScanning/ModuleDepCollector.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang/include/clang/Tooling/Inclusions/HeaderIncludes.h b/clang/include/clang/Tooling/Inclusions/HeaderIncludes.h
index 1466327598151..e7cc1ee382cac 100644
--- a/clang/include/clang/Tooling/Inclusions/HeaderIncludes.h
+++ b/clang/include/clang/Tooling/Inclusions/HeaderIncludes.h
@@ -15,6 +15,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
 #include <list>
+#include <optional>
 #include <unordered_map>
 
 namespace clang {
diff --git a/clang/include/clang/Tooling/Refactoring/ASTSelection.h b/clang/include/clang/Tooling/Refactoring/ASTSelection.h
index c07f8a80e3f21..d9e7c1b844444 100644
--- a/clang/include/clang/Tooling/Refactoring/ASTSelection.h
+++ b/clang/include/clang/Tooling/Refactoring/ASTSelection.h
@@ -14,6 +14,7 @@
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang/include/clang/Tooling/Refactoring/Extract/Extract.h b/clang/include/clang/Tooling/Refactoring/Extract/Extract.h
index e3a8a0d1c84b6..f72d61950d517 100644
--- a/clang/include/clang/Tooling/Refactoring/Extract/Extract.h
+++ b/clang/include/clang/Tooling/Refactoring/Extract/Extract.h
@@ -11,6 +11,7 @@
 
 #include "clang/Tooling/Refactoring/ASTSelection.h"
 #include "clang/Tooling/Refactoring/RefactoringActionRules.h"
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/include/clang/Tooling/Refactoring/RefactoringOptionVisitor.h b/clang/include/clang/Tooling/Refactoring/RefactoringOptionVisitor.h
index f9f85f6eeb82c..327f4707fd969 100644
--- a/clang/include/clang/Tooling/Refactoring/RefactoringOptionVisitor.h
+++ b/clang/include/clang/Tooling/Refactoring/RefactoringOptionVisitor.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLING_REFACTORING_REFACTORINGOPTIONVISITOR_H
 
 #include "clang/Basic/LLVM.h"
+#include <optional>
 #include <type_traits>
 
 namespace clang {
diff --git a/clang/include/clang/Tooling/Refactoring/RefactoringOptions.h b/clang/include/clang/Tooling/Refactoring/RefactoringOptions.h
index 75bd91d150165..963eb2d1c9fec 100644
--- a/clang/include/clang/Tooling/Refactoring/RefactoringOptions.h
+++ b/clang/include/clang/Tooling/Refactoring/RefactoringOptions.h
@@ -14,6 +14,7 @@
 #include "clang/Tooling/Refactoring/RefactoringOption.h"
 #include "clang/Tooling/Refactoring/RefactoringOptionVisitor.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <type_traits>
 
 namespace clang {
diff --git a/clang/include/clang/Tooling/StandaloneExecution.h b/clang/include/clang/Tooling/StandaloneExecution.h
index 8db6229acf7f9..359324f1c5ebf 100644
--- a/clang/include/clang/Tooling/StandaloneExecution.h
+++ b/clang/include/clang/Tooling/StandaloneExecution.h
@@ -15,6 +15,7 @@
 
 #include "clang/Tooling/ArgumentsAdjusters.h"
 #include "clang/Tooling/Execution.h"
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/lib/ARCMigrate/Internals.h b/clang/lib/ARCMigrate/Internals.h
index 33d16fee03594..2c7b8bc7ba4c2 100644
--- a/clang/lib/ARCMigrate/Internals.h
+++ b/clang/lib/ARCMigrate/Internals.h
@@ -15,6 +15,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include <list>
+#include <optional>
 
 namespace clang {
   class ASTContext;
diff --git a/clang/lib/AST/AttrImpl.cpp b/clang/lib/AST/AttrImpl.cpp
index 38d77b845e846..e4e25e21d67f7 100644
--- a/clang/lib/AST/AttrImpl.cpp
+++ b/clang/lib/AST/AttrImpl.cpp
@@ -14,6 +14,7 @@
 #include "clang/AST/Attr.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/Type.h"
+#include <optional>
 using namespace clang;
 
 void LoopHintAttr::printPrettyPragma(raw_ostream &OS,
diff --git a/clang/lib/AST/ComparisonCategories.cpp b/clang/lib/AST/ComparisonCategories.cpp
index f3237854f9d57..2259741cb9c9a 100644
--- a/clang/lib/AST/ComparisonCategories.cpp
+++ b/clang/lib/AST/ComparisonCategories.cpp
@@ -17,6 +17,7 @@
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/Type.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 0e1bc2d68ebda..c0e1290535a59 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -68,6 +68,7 @@
 #include <cstddef>
 #include <cstring>
 #include <memory>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <type_traits>
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index 5fac054b530d2..c6f3ea2dc37f9 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -35,6 +35,7 @@
 #include <cassert>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <utility>
 
 using namespace clang;
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index a735f95427d16..9858fbf85cb80 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -37,6 +37,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cstring>
+#include <optional>
 using namespace clang;
 
 const Expr *Expr::getBestDynamicClassTypeExpr() const {
diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index 81d4bbf0b5451..975287e67c17d 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -38,6 +38,7 @@
 #include <cstddef>
 #include <cstring>
 #include <memory>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/ExternalASTSource.cpp b/clang/lib/AST/ExternalASTSource.cpp
index 091c0cfcc791e..ac522c8a1244e 100644
--- a/clang/lib/AST/ExternalASTSource.cpp
+++ b/clang/lib/AST/ExternalASTSource.cpp
@@ -22,6 +22,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <cstdint>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/FormatString.cpp b/clang/lib/AST/FormatString.cpp
index 4da1fb8889969..3e6d45b4da839 100644
--- a/clang/lib/AST/FormatString.cpp
+++ b/clang/lib/AST/FormatString.cpp
@@ -15,6 +15,7 @@
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/Support/ConvertUTF.h"
+#include <optional>
 
 using clang::analyze_format_string::ArgType;
 using clang::analyze_format_string::FormatStringHandler;
diff --git a/clang/lib/AST/ItaniumCXXABI.cpp b/clang/lib/AST/ItaniumCXXABI.cpp
index ca76861d113a7..10f33e4a3e5e8 100644
--- a/clang/lib/AST/ItaniumCXXABI.cpp
+++ b/clang/lib/AST/ItaniumCXXABI.cpp
@@ -26,6 +26,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/iterator.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 0633e65f388f8..50d6775bb9e85 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -35,6 +35,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/JSONNodeDumper.cpp b/clang/lib/AST/JSONNodeDumper.cpp
index d174919609d79..9ca1d2b71ca1c 100644
--- a/clang/lib/AST/JSONNodeDumper.cpp
+++ b/clang/lib/AST/JSONNodeDumper.cpp
@@ -3,6 +3,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/Linkage.h b/clang/lib/AST/Linkage.h
index f4c697c7f6ae8..e1c0f92074fed 100644
--- a/clang/lib/AST/Linkage.h
+++ b/clang/lib/AST/Linkage.h
@@ -21,6 +21,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/PointerIntPair.h"
+#include <optional>
 
 namespace clang {
 /// Kinds of LV computation.  The linkage side of the computation is
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 155de899fd42e..2748fd6206155 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -35,6 +35,7 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/StringSaver.h"
 #include "llvm/Support/xxhash.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/NSAPI.cpp b/clang/lib/AST/NSAPI.cpp
index db301e7a30d7c..81c8f7667ab12 100644
--- a/clang/lib/AST/NSAPI.cpp
+++ b/clang/lib/AST/NSAPI.cpp
@@ -11,6 +11,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/Expr.h"
 #include "llvm/ADT/StringSwitch.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/OpenMPClause.cpp b/clang/lib/AST/OpenMPClause.cpp
index abbfdca9da362..d795b703bd4f9 100644
--- a/clang/lib/AST/OpenMPClause.cpp
+++ b/clang/lib/AST/OpenMPClause.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
+#include <optional>
 
 using namespace clang;
 using namespace llvm;
diff --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index 4081ae8d8b777..3e65543454fae 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -41,6 +41,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstring>
+#include <optional>
 #include <string>
 #include <type_traits>
 #include <utility>
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 1e0d8a5046755..d561685719e72 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -54,6 +54,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang/lib/AST/TemplateBase.cpp b/clang/lib/AST/TemplateBase.cpp
index bd3a3e9d9cf14..c5a8895318f47 100644
--- a/clang/lib/AST/TemplateBase.cpp
+++ b/clang/lib/AST/TemplateBase.cpp
@@ -40,6 +40,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/AST/TemplateName.cpp b/clang/lib/AST/TemplateName.cpp
index f0e3e94f43c24..a16f83538143f 100644
--- a/clang/lib/AST/TemplateName.cpp
+++ b/clang/lib/AST/TemplateName.cpp
@@ -29,6 +29,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index 1536faed23b02..cac105844f2d0 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -50,6 +50,7 @@
 #include <cassert>
 #include <cstdint>
 #include <cstring>
+#include <optional>
 #include <type_traits>
 
 using namespace clang;
diff --git a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
index f9a1a59401aca..9e755fa271bed 100644
--- a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
+++ b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
@@ -34,6 +34,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp b/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp
index 31cb57af873c5..04e7d3cd5d285 100644
--- a/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Regex.h"
+#include <optional>
 #include <string>
 
 static llvm::Optional<std::string>
diff --git a/clang/lib/ASTMatchers/Dynamic/Marshallers.h b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
index 758205b6811b0..c6bd6d51af1e3 100644
--- a/clang/lib/ASTMatchers/Dynamic/Marshallers.h
+++ b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
@@ -40,6 +40,7 @@
 #include <iterator>
 #include <limits>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/ASTMatchers/Dynamic/Parser.cpp b/clang/lib/ASTMatchers/Dynamic/Parser.cpp
index b9af50990af95..ac6d643c95601 100644
--- a/clang/lib/ASTMatchers/Dynamic/Parser.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Parser.cpp
@@ -25,6 +25,7 @@
 #include <cerrno>
 #include <cstddef>
 #include <cstdlib>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/ASTMatchers/Dynamic/Registry.cpp b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
index 4c20a1295a8da..2fb51c70649f5 100644
--- a/clang/lib/ASTMatchers/Dynamic/Registry.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
@@ -26,6 +26,7 @@
 #include <cassert>
 #include <iterator>
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 #include <utility>
diff --git a/clang/lib/ASTMatchers/Dynamic/VariantValue.cpp b/clang/lib/ASTMatchers/Dynamic/VariantValue.cpp
index 6cf4df4bef13d..ee60042570036 100644
--- a/clang/lib/ASTMatchers/Dynamic/VariantValue.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/VariantValue.cpp
@@ -14,6 +14,7 @@
 #include "clang/ASTMatchers/Dynamic/VariantValue.h"
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 namespace clang {
 namespace ast_matchers {
diff --git a/clang/lib/Analysis/BodyFarm.cpp b/clang/lib/Analysis/BodyFarm.cpp
index cf9c22fafe258..e5fa481dcf657 100644
--- a/clang/lib/Analysis/BodyFarm.cpp
+++ b/clang/lib/Analysis/BodyFarm.cpp
@@ -24,6 +24,7 @@
 #include "clang/Basic/OperatorKinds.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/Debug.h"
+#include <optional>
 
 #define DEBUG_TYPE "body-farm"
 
diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index 7f2c8340cdce3..dd1de75dd6ff5 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -56,6 +56,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <utility>
diff --git a/clang/lib/Analysis/CFGStmtMap.cpp b/clang/lib/Analysis/CFGStmtMap.cpp
index d1c23e3c879b4..82f151c95f753 100644
--- a/clang/lib/Analysis/CFGStmtMap.cpp
+++ b/clang/lib/Analysis/CFGStmtMap.cpp
@@ -15,6 +15,7 @@
 #include "clang/AST/ParentMap.h"
 #include "clang/Analysis/CFG.h"
 #include "clang/Analysis/CFGStmtMap.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Analysis/CalledOnceCheck.cpp b/clang/lib/Analysis/CalledOnceCheck.cpp
index 896562ca3bb46..d68182dd5b5cf 100644
--- a/clang/lib/Analysis/CalledOnceCheck.cpp
+++ b/clang/lib/Analysis/CalledOnceCheck.cpp
@@ -38,6 +38,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <memory>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Analysis/Consumed.cpp b/clang/lib/Analysis/Consumed.cpp
index 9560248b173fb..287dfbb0971e7 100644
--- a/clang/lib/Analysis/Consumed.cpp
+++ b/clang/lib/Analysis/Consumed.cpp
@@ -34,6 +34,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <utility>
 
 // TODO: Adjust states of args to constructors in the same way that arguments to
diff --git a/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp b/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
index 94e0b513af844..c0eb256b9e308 100644
--- a/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
index 685df7b99fc03..44523a2e45366 100644
--- a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -13,6 +13,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <optional>
 #include <system_error>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/Analysis/IssueHash.cpp b/clang/lib/Analysis/IssueHash.cpp
index 94816747668da..3e712fc173213 100644
--- a/clang/lib/Analysis/IssueHash.cpp
+++ b/clang/lib/Analysis/IssueHash.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Support/Path.h"
 
 #include <functional>
+#include <optional>
 #include <sstream>
 #include <string>
 
diff --git a/clang/lib/Analysis/LiveVariables.cpp b/clang/lib/Analysis/LiveVariables.cpp
index ff7f3ebe28f89..d9194dd263792 100644
--- a/clang/lib/Analysis/LiveVariables.cpp
+++ b/clang/lib/Analysis/LiveVariables.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
+#include <optional>
 #include <vector>
 
 using namespace clang;
diff --git a/clang/lib/Analysis/MacroExpansionContext.cpp b/clang/lib/Analysis/MacroExpansionContext.cpp
index 0fb9c6a894aa9..3d98be7d64767 100644
--- a/clang/lib/Analysis/MacroExpansionContext.cpp
+++ b/clang/lib/Analysis/MacroExpansionContext.cpp
@@ -8,6 +8,7 @@
 
 #include "clang/Analysis/MacroExpansionContext.h"
 #include "llvm/Support/Debug.h"
+#include <optional>
 
 #define DEBUG_TYPE "macro-expansion-context"
 
diff --git a/clang/lib/Analysis/PathDiagnostic.cpp b/clang/lib/Analysis/PathDiagnostic.cpp
index e2a20a0f85151..42fa40175f208 100644
--- a/clang/lib/Analysis/PathDiagnostic.cpp
+++ b/clang/lib/Analysis/PathDiagnostic.cpp
@@ -44,6 +44,7 @@
 #include <cassert>
 #include <cstring>
 #include <memory>
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/lib/Analysis/ReachableCode.cpp b/clang/lib/Analysis/ReachableCode.cpp
index ce0f4f83ba04f..a375521d410d0 100644
--- a/clang/lib/Analysis/ReachableCode.cpp
+++ b/clang/lib/Analysis/ReachableCode.cpp
@@ -24,6 +24,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Analysis/RetainSummaryManager.cpp b/clang/lib/Analysis/RetainSummaryManager.cpp
index f17ad9100ce44..30b37ccec87e3 100644
--- a/clang/lib/Analysis/RetainSummaryManager.cpp
+++ b/clang/lib/Analysis/RetainSummaryManager.cpp
@@ -19,6 +19,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/ParentMap.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/Analysis/ThreadSafety.cpp b/clang/lib/Analysis/ThreadSafety.cpp
index 76747561a9a3b..feaca521a1c81 100644
--- a/clang/lib/Analysis/ThreadSafety.cpp
+++ b/clang/lib/Analysis/ThreadSafety.cpp
@@ -53,6 +53,7 @@
 #include <functional>
 #include <iterator>
 #include <memory>
+#include <optional>
 #include <string>
 #include <type_traits>
 #include <utility>
diff --git a/clang/lib/Analysis/UninitializedValues.cpp b/clang/lib/Analysis/UninitializedValues.cpp
index e2f1f6e897d46..ae5c3541f15ba 100644
--- a/clang/lib/Analysis/UninitializedValues.cpp
+++ b/clang/lib/Analysis/UninitializedValues.cpp
@@ -35,6 +35,7 @@
 #include "llvm/Support/Casting.h"
 #include <algorithm>
 #include <cassert>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Analysis/UnsafeBufferUsage.cpp b/clang/lib/Analysis/UnsafeBufferUsage.cpp
index 7dd9e918b0c2e..43713b40447b8 100644
--- a/clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ b/clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -10,6 +10,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang/lib/Basic/DiagnosticIDs.cpp b/clang/lib/Basic/DiagnosticIDs.cpp
index 66f397974af56..0b06a29335dda 100644
--- a/clang/lib/Basic/DiagnosticIDs.cpp
+++ b/clang/lib/Basic/DiagnosticIDs.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <map>
+#include <optional>
 using namespace clang;
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/Basic/ProfileList.cpp b/clang/lib/Basic/ProfileList.cpp
index 0f049b11f52f6..136924f91607b 100644
--- a/clang/lib/Basic/ProfileList.cpp
+++ b/clang/lib/Basic/ProfileList.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Support/SpecialCaseList.h"
 
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Basic/Sarif.cpp b/clang/lib/Basic/Sarif.cpp
index 2c1eebc128700..52f22f2c4b834 100644
--- a/clang/lib/Basic/Sarif.cpp
+++ b/clang/lib/Basic/Sarif.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/Path.h"
 
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 63dd4d64fea18..6fbeb38b7c411 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -38,6 +38,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <tuple>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index d7893c1139f15..40977964d940f 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/AArch64TargetParser.h"
 #include "llvm/Support/ARMTargetParserCommon.h"
+#include <optional>
 
 using namespace clang;
 using namespace clang::targets;
diff --git a/clang/lib/Basic/Targets/AArch64.h b/clang/lib/Basic/Targets/AArch64.h
index 95edf6995f9e4..33d5d11aeed75 100644
--- a/clang/lib/Basic/Targets/AArch64.h
+++ b/clang/lib/Basic/Targets/AArch64.h
@@ -16,6 +16,7 @@
 #include "OSTargets.h"
 #include "clang/Basic/TargetBuiltins.h"
 #include "llvm/Support/AArch64TargetParser.h"
+#include <optional>
 
 namespace clang {
 namespace targets {
diff --git a/clang/lib/Basic/Targets/M68k.cpp b/clang/lib/Basic/Targets/M68k.cpp
index 868437c62cd07..be3ab8938d065 100644
--- a/clang/lib/Basic/Targets/M68k.cpp
+++ b/clang/lib/Basic/Targets/M68k.cpp
@@ -21,6 +21,7 @@
 #include <cstdint>
 #include <cstring>
 #include <limits>
+#include <optional>
 
 namespace clang {
 namespace targets {
diff --git a/clang/lib/Basic/Targets/M68k.h b/clang/lib/Basic/Targets/M68k.h
index a42ca674ef9cc..b68baeb97fc81 100644
--- a/clang/lib/Basic/Targets/M68k.h
+++ b/clang/lib/Basic/Targets/M68k.h
@@ -18,6 +18,7 @@
 #include "clang/Basic/TargetOptions.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Support/Compiler.h"
+#include <optional>
 
 namespace clang {
 namespace targets {
diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
index 47096bd23f95b..30988ae83e4ed 100644
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Triple.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/RISCVISAInfo.h"
+#include <optional>
 
 namespace clang {
 namespace targets {
diff --git a/clang/lib/Basic/Targets/X86.cpp b/clang/lib/Basic/Targets/X86.cpp
index a6eea30311d3d..affe20325bede 100644
--- a/clang/lib/Basic/Targets/X86.cpp
+++ b/clang/lib/Basic/Targets/X86.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/X86TargetParser.h"
+#include <optional>
 
 namespace clang {
 namespace targets {
diff --git a/clang/lib/Basic/Targets/X86.h b/clang/lib/Basic/Targets/X86.h
index 3a02889f9f6dc..ef38c771c2d8e 100644
--- a/clang/lib/Basic/Targets/X86.h
+++ b/clang/lib/Basic/Targets/X86.h
@@ -20,6 +20,7 @@
 #include "llvm/ADT/Triple.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/X86TargetParser.h"
+#include <optional>
 
 namespace clang {
 namespace targets {
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 479e24245df4d..3bbcb1ee708ed 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -56,6 +56,7 @@
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/X86TargetParser.h"
+#include <optional>
 #include <sstream>
 
 using namespace clang;
diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index bf3b0c3d74825..ec09c74fa939e 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -29,6 +29,7 @@
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/Transforms/Utils/SanitizerStats.h"
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 02e3790a45ebc..764afedf6069a 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -37,6 +37,7 @@
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/Type.h"
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index ca665dbe7d0a9..213f6b70468f7 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -42,6 +42,7 @@
 #include "llvm/Support/SaveAndRestore.h"
 #include "llvm/Transforms/Utils/SanitizerStats.h"
 
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index 8e74f0295301a..28c4a82200d3b 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -29,6 +29,7 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalVariable.h"
+#include <optional>
 using namespace clang;
 using namespace CodeGen;
 
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index b4c1966c69620..992edc012f351 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -43,6 +43,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/Support/TypeSize.h"
 #include <cstdarg>
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index 5cc2c89da0f8c..29a849c18a2b9 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Frontend/HLSL/HLSLResource.h"
 
+#include <optional>
 #include <vector>
 
 namespace llvm {
diff --git a/clang/lib/CodeGen/CGLoopInfo.cpp b/clang/lib/CodeGen/CGLoopInfo.cpp
index d2b0f16f04e62..d6036fdc782aa 100644
--- a/clang/lib/CodeGen/CGLoopInfo.cpp
+++ b/clang/lib/CodeGen/CGLoopInfo.cpp
@@ -17,6 +17,7 @@
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Metadata.h"
+#include <optional>
 using namespace clang::CodeGen;
 using namespace llvm;
 
diff --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
index 42c766a3ec0e6..200396b60065b 100644
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -29,6 +29,7 @@
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/InlineAsm.h"
+#include <optional>
 using namespace clang;
 using namespace CodeGen;
 
diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index 2b99b302c38d0..d766263c20ee3 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -42,6 +42,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <numeric>
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 28203494f2b19..ce7ab9ef61d64 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -32,6 +32,7 @@
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/Support/SaveAndRestore.h"
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index 65fd2a6e45fa1..27f44f192d595 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -34,6 +34,7 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/Support/AtomicOrdering.h"
+#include <optional>
 using namespace clang;
 using namespace CodeGen;
 using namespace llvm::omp;
diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 4b8e1d8623598..083d6b65a7356 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -49,6 +49,7 @@
 #include "llvm/Transforms/IPO/Internalize.h"
 
 #include <memory>
+#include <optional>
 using namespace clang;
 using namespace llvm;
 
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index f8617f96459da..6dafd4a9cc09d 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -46,6 +46,7 @@
 #include "llvm/Support/CRC.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 5282874da7119..10b92718c1152 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -41,6 +41,7 @@
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Transforms/Utils/SanitizerStats.h"
+#include <optional>
 
 namespace llvm {
 class BasicBlock;
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 6e37676858c34..446874fd7d377 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -69,6 +69,7 @@
 #include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/X86TargetParser.h"
 #include "llvm/Support/xxhash.h"
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index d23f5a9d90df2..689d55455ea23 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -36,6 +36,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Transforms/Utils/SanitizerStats.h"
+#include <optional>
 
 namespace llvm {
 class Module;
diff --git a/clang/lib/CodeGen/CodeGenPGO.cpp b/clang/lib/CodeGen/CodeGenPGO.cpp
index 6ee052d6a838f..c581af2d4bb45 100644
--- a/clang/lib/CodeGen/CodeGenPGO.cpp
+++ b/clang/lib/CodeGen/CodeGenPGO.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MD5.h"
+#include <optional>
 
 static llvm::cl::opt<bool>
     EnableValueProfiling("enable-value-profiling",
diff --git a/clang/lib/CodeGen/CodeGenPGO.h b/clang/lib/CodeGen/CodeGenPGO.h
index 7ebd42a4593ee..048251ffdec1b 100644
--- a/clang/lib/CodeGen/CodeGenPGO.h
+++ b/clang/lib/CodeGen/CodeGenPGO.h
@@ -19,6 +19,7 @@
 #include "llvm/ProfileData/InstrProfReader.h"
 #include <array>
 #include <memory>
+#include <optional>
 
 namespace clang {
 namespace CodeGen {
diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 14db4f0cbbca2..3fd7f10df347e 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -26,6 +26,7 @@
 #include "llvm/ProfileData/InstrProfReader.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 // This selects the coverage mapping format defined when `InstrProfData.inc`
 // is textually included.
diff --git a/clang/lib/CodeGen/SwiftCallingConv.cpp b/clang/lib/CodeGen/SwiftCallingConv.cpp
index d4c6c9614e053..982067c403c72 100644
--- a/clang/lib/CodeGen/SwiftCallingConv.cpp
+++ b/clang/lib/CodeGen/SwiftCallingConv.cpp
@@ -15,6 +15,7 @@
 #include "CodeGenModule.h"
 #include "TargetInfo.h"
 #include "clang/Basic/TargetInfo.h"
+#include <optional>
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/clang/lib/CrossTU/CrossTranslationUnit.cpp b/clang/lib/CrossTU/CrossTranslationUnit.cpp
index c4983ea7965ff..a871eee5ac9db 100644
--- a/clang/lib/CrossTU/CrossTranslationUnit.cpp
+++ b/clang/lib/CrossTU/CrossTranslationUnit.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <fstream>
+#include <optional>
 #include <sstream>
 #include <tuple>
 
diff --git a/clang/lib/Edit/RewriteObjCFoundationAPI.cpp b/clang/lib/Edit/RewriteObjCFoundationAPI.cpp
index 1fe6a2d68525a..89dbc967d93e9 100644
--- a/clang/lib/Edit/RewriteObjCFoundationAPI.cpp
+++ b/clang/lib/Edit/RewriteObjCFoundationAPI.cpp
@@ -18,6 +18,7 @@
 #include "clang/AST/ParentMap.h"
 #include "clang/Edit/Commit.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 using namespace clang;
 using namespace edit;
diff --git a/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp b/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
index 5c7ab654c05c9..91b86bdaffb74 100644
--- a/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
+++ b/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/VersionTuple.h"
+#include <optional>
 #include <type_traits>
 
 using namespace clang;
diff --git a/clang/lib/Format/ContinuationIndenter.h b/clang/lib/Format/ContinuationIndenter.h
index 620060e688614..6b4d5b6fa1650 100644
--- a/clang/lib/Format/ContinuationIndenter.h
+++ b/clang/lib/Format/ContinuationIndenter.h
@@ -20,6 +20,7 @@
 #include "clang/Format/Format.h"
 #include "llvm/Support/Regex.h"
 #include <map>
+#include <optional>
 #include <tuple>
 
 namespace clang {
diff --git a/clang/lib/Format/FormatToken.h b/clang/lib/Format/FormatToken.h
index d8c18a5f89d32..61a395e5aa48f 100644
--- a/clang/lib/Format/FormatToken.h
+++ b/clang/lib/Format/FormatToken.h
@@ -20,6 +20,7 @@
 #include "clang/Format/Format.h"
 #include "clang/Lex/Lexer.h"
 #include <memory>
+#include <optional>
 #include <unordered_set>
 
 namespace clang {
diff --git a/clang/lib/Frontend/DependencyFile.cpp b/clang/lib/Frontend/DependencyFile.cpp
index e19ccdf78e423..1c175c7ee6bde 100644
--- a/clang/lib/Frontend/DependencyFile.cpp
+++ b/clang/lib/Frontend/DependencyFile.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index f3c2afc2e880a..fa9ec465743c1 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
 #include <memory>
+#include <optional>
 #include <system_error>
 
 using namespace clang;
diff --git a/clang/lib/Lex/DependencyDirectivesScanner.cpp b/clang/lib/Lex/DependencyDirectivesScanner.cpp
index 183be4f5dc7ee..c932c0d838282 100644
--- a/clang/lib/Lex/DependencyDirectivesScanner.cpp
+++ b/clang/lib/Lex/DependencyDirectivesScanner.cpp
@@ -23,6 +23,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSwitch.h"
+#include <optional>
 
 using namespace clang;
 using namespace clang::dependency_directives_scan;
diff --git a/clang/lib/Lex/HeaderMap.cpp b/clang/lib/Lex/HeaderMap.cpp
index 2512552c0f1a9..2a444b5211b44 100644
--- a/clang/lib/Lex/HeaderMap.cpp
+++ b/clang/lib/Lex/HeaderMap.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/Debug.h"
 #include <cstring>
 #include <memory>
+#include <optional>
 using namespace clang;
 
 /// HashHMapKey - This is the 'well known' hash function required by the file
diff --git a/clang/lib/Lex/InitHeaderSearch.cpp b/clang/lib/Lex/InitHeaderSearch.cpp
index d55746b346214..4b527ac56b000 100644
--- a/clang/lib/Lex/InitHeaderSearch.cpp
+++ b/clang/lib/Lex/InitHeaderSearch.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace clang::frontend;
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index ce48e7da21bb3..9965acbc10de1 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -43,6 +43,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <utility>
diff --git a/clang/lib/Lex/MacroInfo.cpp b/clang/lib/Lex/MacroInfo.cpp
index bfac365c9d7dc..819bb726b3e3f 100644
--- a/clang/lib/Lex/MacroInfo.cpp
+++ b/clang/lib/Lex/MacroInfo.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
+#include <optional>
 #include <utility>
 
 using namespace clang;
diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index 633ea26fc08a1..7292f16aa50cc 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -46,6 +46,7 @@
 #include <cassert>
 #include <cstdint>
 #include <cstring>
+#include <optional>
 #include <string>
 #include <system_error>
 #include <utility>
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 8a38fb41d43ad..3064c8c210818 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -47,6 +47,7 @@
 #include <cassert>
 #include <cstring>
 #include <new>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/lib/Lex/PPLexerChange.cpp b/clang/lib/Lex/PPLexerChange.cpp
index 570728e7b3162..c997bc35008e3 100644
--- a/clang/lib/Lex/PPLexerChange.cpp
+++ b/clang/lib/Lex/PPLexerChange.cpp
@@ -22,6 +22,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBufferRef.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 9262d1c2ad83f..cd60452696a12 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -53,6 +53,7 @@
 #include <cstddef>
 #include <cstring>
 #include <ctime>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <utility>
diff --git a/clang/lib/Lex/Pragma.cpp b/clang/lib/Lex/Pragma.cpp
index fc86f7da32361..ab61c727a8dd6 100644
--- a/clang/lib/Lex/Pragma.cpp
+++ b/clang/lib/Lex/Pragma.cpp
@@ -48,6 +48,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <limits>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/Lex/PreprocessingRecord.cpp b/clang/lib/Lex/PreprocessingRecord.cpp
index 1b13d09f23498..e187fb60c31d6 100644
--- a/clang/lib/Lex/PreprocessingRecord.cpp
+++ b/clang/lib/Lex/PreprocessingRecord.cpp
@@ -31,6 +31,7 @@
 #include <cstddef>
 #include <cstring>
 #include <iterator>
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
index 5f54c3b9e7539..87655c78cb6b5 100644
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -65,6 +65,7 @@
 #include <algorithm>
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/Lex/TokenLexer.cpp b/clang/lib/Lex/TokenLexer.cpp
index a64a00d8460fc..6f801dbbf6b56 100644
--- a/clang/lib/Lex/TokenLexer.cpp
+++ b/clang/lib/Lex/TokenLexer.cpp
@@ -31,6 +31,7 @@
 #include "llvm/ADT/iterator_range.h"
 #include <cassert>
 #include <cstring>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 241a46193d5fe..eec12a14a2ca7 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -29,6 +29,7 @@
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringSwitch.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 6fbf804360116..1dadb769417b2 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -27,6 +27,7 @@
 #include "clang/Sema/Scope.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/TimeProfiler.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 34fead3478004..ab3b77d90d8f6 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -30,6 +30,7 @@
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/TypoCorrection.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 using namespace clang;
 
 /// Simple precedence-based parser for binary/ternary operators.
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 680cae705fcce..b5e6d011ecd69 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -25,6 +25,7 @@
 #include "llvm/ADT/UniqueVector.h"
 #include "llvm/Frontend/OpenMP/OMPAssume.h"
 #include "llvm/Frontend/OpenMP/OMPContext.h"
+#include <optional>
 
 using namespace clang;
 using namespace llvm::omp;
diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index d157536bc02fa..445ad64de9677 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -22,6 +22,7 @@
 #include "clang/Sema/Scope.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringSwitch.h"
+#include <optional>
 using namespace clang;
 
 namespace {
diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index e16021878b9ec..9f3a4cb904f74 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -22,6 +22,7 @@
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/TypoCorrection.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index 7f0677f3376f1..13960fd1867da 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -48,6 +48,7 @@
 #include <algorithm>
 #include <deque>
 #include <iterator>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index e856e5a4429c8..19c75c7e08421 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -49,6 +49,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Support/TimeProfiler.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaAttr.cpp b/clang/lib/Sema/SemaAttr.cpp
index 6b4777d1f05f0..572eb16eb7cc5 100644
--- a/clang/lib/Sema/SemaAttr.cpp
+++ b/clang/lib/Sema/SemaAttr.cpp
@@ -18,6 +18,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/SemaInternal.h"
+#include <optional>
 using namespace clang;
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/Sema/SemaAvailability.cpp b/clang/lib/Sema/SemaAvailability.cpp
index 316c01309a8c6..e5aeaaddad539 100644
--- a/clang/lib/Sema/SemaAvailability.cpp
+++ b/clang/lib/Sema/SemaAvailability.cpp
@@ -19,6 +19,7 @@
 #include "clang/Sema/DelayedDiagnostic.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/Sema.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaCUDA.cpp b/clang/lib/Sema/SemaCUDA.cpp
index 01349f41e84cb..58063dfd22606 100644
--- a/clang/lib/Sema/SemaCUDA.cpp
+++ b/clang/lib/Sema/SemaCUDA.cpp
@@ -24,6 +24,7 @@
 #include "clang/Sema/Template.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 using namespace clang;
 
 template <typename AttrT> static bool hasExplicitAttr(const VarDecl *D) {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 1d956fadcf670..5bd1072cf9fcb 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -95,6 +95,7 @@
 #include <cstdint>
 #include <functional>
 #include <limits>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <utility>
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 9a0446e77d1e3..0bc264cbaae1b 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -56,6 +56,7 @@
 
 #include <list>
 #include <map>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index 3ab93827cd311..6b3bb0d22060a 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -26,6 +26,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/StringExtras.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 9ab53f56d29cb..44657a1cc1689 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -50,6 +50,7 @@
 #include <algorithm>
 #include <cstring>
 #include <functional>
+#include <optional>
 #include <unordered_map>
 
 using namespace clang;
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 1410104f43f70..90322051839de 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -47,6 +47,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 96d57f4506814..0c8cb7b5e219b 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -46,6 +46,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include <map>
+#include <optional>
 #include <set>
 
 using namespace clang;
diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index 1786f3112d1a4..6fe0575bf24e7 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -21,6 +21,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 93eaed1a92b1b..710befee15b17 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -56,6 +56,7 @@
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include "llvm/Support/TypeSize.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 080a0de4bc188..08dd6f751960f 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -44,6 +44,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/TypeSize.h"
+#include <optional>
 using namespace clang;
 using namespace sema;
 
diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
index 9db813ed37696..abd104b4fdfa4 100644
--- a/clang/lib/Sema/SemaExprObjC.cpp
+++ b/clang/lib/Sema/SemaExprObjC.cpp
@@ -27,6 +27,7 @@
 #include "clang/Sema/SemaInternal.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/ConvertUTF.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index 3e8b2cf3c71d0..1e4b638e3aadc 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -21,6 +21,7 @@
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/SemaLambda.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 using namespace clang;
 using namespace sema;
 
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index dedcfb530df86..cea8b4246fccf 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -45,6 +45,7 @@
 #include <algorithm>
 #include <iterator>
 #include <list>
+#include <optional>
 #include <set>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index 0adcc6856e098..60b4a86c1a4ef 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -15,6 +15,7 @@
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/SemaInternal.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index f48707d73b734..09c21a41550a7 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -39,6 +39,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Frontend/OpenMP/OMPAssume.h"
 #include "llvm/Frontend/OpenMP/OMPConstants.h"
+#include <optional>
 #include <set>
 
 using namespace clang;
diff --git a/clang/lib/Sema/SemaRISCVVectorLookup.cpp b/clang/lib/Sema/SemaRISCVVectorLookup.cpp
index 8e730648e8be6..13f9aeb8e9458 100644
--- a/clang/lib/Sema/SemaRISCVVectorLookup.cpp
+++ b/clang/lib/Sema/SemaRISCVVectorLookup.cpp
@@ -20,6 +20,7 @@
 #include "clang/Sema/Sema.h"
 #include "clang/Support/RISCVVIntrinsicUtils.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang/lib/Sema/SemaStmtAsm.cpp b/clang/lib/Sema/SemaStmtAsm.cpp
index 06fc0ec798660..191d7472dfcf5 100644
--- a/clang/lib/Sema/SemaStmtAsm.cpp
+++ b/clang/lib/Sema/SemaStmtAsm.cpp
@@ -24,6 +24,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/MC/MCParser/MCAsmParser.h"
+#include <optional>
 using namespace clang;
 using namespace sema;
 
diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
index 9ec8fe21d0a29..27a08d3a5b2e9 100644
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -19,6 +19,7 @@
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaInternal.h"
 #include "llvm/ADT/StringExtras.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index cfa28e4336874..27b59067e182e 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -39,6 +39,7 @@
 #include "llvm/ADT/StringExtras.h"
 
 #include <iterator>
+#include <optional>
 using namespace clang;
 using namespace sema;
 
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index c77b0afdba3d8..4a5305a54889c 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -54,6 +54,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
+#include <optional>
 #include <tuple>
 #include <type_traits>
 #include <utility>
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 097203a1c87e9..e1329c4b23c5a 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -36,6 +36,7 @@
 #include "clang/Sema/TemplateInstCallback.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/TimeProfiler.h"
+#include <optional>
 
 using namespace clang;
 using namespace sema;
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 7d6f2823a19ff..04d3a058de14e 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -29,6 +29,7 @@
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateInstCallback.h"
 #include "llvm/Support/TimeProfiler.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Sema/SemaTemplateVariadic.cpp b/clang/lib/Sema/SemaTemplateVariadic.cpp
index 3326b93c085c6..95a7478201421 100644
--- a/clang/lib/Sema/SemaTemplateVariadic.cpp
+++ b/clang/lib/Sema/SemaTemplateVariadic.cpp
@@ -18,6 +18,7 @@
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/Template.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 04d34f3887def..6e8ed7ce8c4d3 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -41,6 +41,7 @@
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <bitset>
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index b608d53331032..8d4f30b1b4718 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -40,6 +40,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
+#include <optional>
 
 using namespace llvm::omp;
 
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index c47a56b075f9b..2e920e29adb80 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -135,6 +135,7 @@
 #include <limits>
 #include <map>
 #include <memory>
+#include <optional>
 #include <string>
 #include <system_error>
 #include <tuple>
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 6c8e0bd7ad1e8..b87e9ace9c4ed 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -61,6 +61,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index af3367f2d1056..2a5618f0c0d61 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -111,6 +111,7 @@
 #include <ctime>
 #include <limits>
 #include <memory>
+#include <optional>
 #include <queue>
 #include <tuple>
 #include <utility>
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index a63d010b17ca4..2b1001ab5046c 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -23,6 +23,7 @@
 #include "clang/Serialization/ASTRecordWriter.h"
 #include "llvm/Bitstream/BitstreamWriter.h"
 #include "llvm/Support/ErrorHandling.h"
+#include <optional>
 using namespace clang;
 using namespace serialization;
 
diff --git a/clang/lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp
index 6154eeb3419c0..a2390d479527c 100644
--- a/clang/lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/ArrayBoundCheckerV2.cpp b/clang/lib/StaticAnalyzer/Checkers/ArrayBoundCheckerV2.cpp
index 5be5bcde4d6ef..bf3c92eec19bc 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ArrayBoundCheckerV2.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ArrayBoundCheckerV2.cpp
@@ -23,6 +23,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp
index dad25d6f853b1..2175b34118e25 100644
--- a/clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp
@@ -17,6 +17,7 @@
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
index cd760b1ae62ec..e6857ce76cb51 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -27,6 +27,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/raw_ostream.h"
 #include <functional>
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp
index 45f9a82a9d0a4..92ada1f9fd4d9 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp
@@ -25,6 +25,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicType.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 #include <utility>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
index a45927ef3a3ea..a5e26b3463b27 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
@@ -45,6 +45,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
index bfd1d4c162ec3..0f04ae6d0c468 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
@@ -17,6 +17,7 @@
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp b/clang/lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp
index aaf8cca32b606..20374ffc4cdfc 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp
@@ -31,6 +31,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicType.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp
index e5088fb266bc2..12490801470b0 100644
--- a/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp
@@ -22,6 +22,7 @@
 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/ErrnoChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ErrnoChecker.cpp
index 2011a042e0e91..0a1b220fc20be 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ErrnoChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ErrnoChecker.cpp
@@ -22,6 +22,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.cpp b/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.cpp
index 4f5a5793a0b7c..ade172c62ef85 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.cpp
@@ -28,6 +28,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.h b/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.h
index 975fe1b48556c..765c6716ef80e 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.h
+++ b/clang/lib/StaticAnalyzer/Checkers/ErrnoModeling.h
@@ -16,6 +16,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
+#include <optional>
 
 namespace clang {
 namespace ento {
diff --git a/clang/lib/StaticAnalyzer/Checkers/ErrnoTesterChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ErrnoTesterChecker.cpp
index 3b9ff0cca0fa3..9d09393c67c67 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ErrnoTesterChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ErrnoTesterChecker.cpp
@@ -17,6 +17,7 @@
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
index d298bb37ce4f0..3733e58190abc 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
@@ -17,6 +17,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicExtent.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/ScopedPrinter.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp
index eb3b89ee6c5ca..c0934832bb229 100644
--- a/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp
@@ -101,6 +101,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
 #include "llvm/ADT/StringExtras.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/GTestChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/GTestChecker.cpp
index dbfdff4d2a3b1..e9a577bd32105 100644
--- a/clang/lib/StaticAnalyzer/Checkers/GTestChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/GTestChecker.cpp
@@ -20,6 +20,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
index 9870746cbe0ca..6b0b6c683cf68 100644
--- a/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
@@ -29,6 +29,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "llvm/Support/Unicode.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/MIGChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MIGChecker.cpp
index 6952953627e30..b5f39160823a4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MIGChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MIGChecker.cpp
@@ -30,6 +30,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/MacOSKeychainAPIChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MacOSKeychainAPIChecker.cpp
index 635eb00e4ca95..65867dca88a4e 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MacOSKeychainAPIChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MacOSKeychainAPIChecker.cpp
@@ -21,6 +21,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
index a6e8fcd425d5d..9fba90d06a134 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
@@ -24,6 +24,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
 #include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 #include <utility>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp
index c9b17a56b224d..6226c0e166c4a 100644
--- a/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp
@@ -24,6 +24,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/NonnullGlobalConstantsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/NonnullGlobalConstantsChecker.cpp
index 9a15f4568fc5d..e92cbae3e8c86 100644
--- a/clang/lib/StaticAnalyzer/Checkers/NonnullGlobalConstantsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/NonnullGlobalConstantsChecker.cpp
@@ -26,6 +26,7 @@
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountChecker.cpp
index 2e00bcdfd9322..e52a54a19a63a 100644
--- a/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountChecker.cpp
@@ -14,6 +14,7 @@
 #include "RetainCountChecker.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/ReturnValueChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ReturnValueChecker.cpp
index 9eeb450654a24..baf443c09ca9f 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ReturnValueChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ReturnValueChecker.cpp
@@ -19,6 +19,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp b/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
index 107ff5aa0d9d0..5b921e791c8a4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
@@ -33,6 +33,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/ErrorHandling.h"
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
index 4af6a69edd6a3..8ce8c4f1ae6b7 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
@@ -22,6 +22,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
 #include <functional>
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/Taint.cpp b/clang/lib/StaticAnalyzer/Checkers/Taint.cpp
index 44162094e49a8..e20895f54eac7 100644
--- a/clang/lib/StaticAnalyzer/Checkers/Taint.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/Taint.cpp
@@ -13,6 +13,7 @@
 #include "clang/StaticAnalyzer/Checkers/Taint.h"
 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/TestAfterDivZeroChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/TestAfterDivZeroChecker.cpp
index eeec807ccee40..ce43c55d1ff49 100644
--- a/clang/lib/StaticAnalyzer/Checkers/TestAfterDivZeroChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/TestAfterDivZeroChecker.cpp
@@ -17,6 +17,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "llvm/ADT/FoldingSet.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/UndefBranchChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UndefBranchChecker.cpp
index ebe5ad53cc303..8146d3078d694 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UndefBranchChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UndefBranchChecker.cpp
@@ -18,6 +18,7 @@
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include <optional>
 #include <utility>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Checkers/UndefCapturedBlockVarChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UndefCapturedBlockVarChecker.cpp
index 816a547cadc3d..c0dd5f9462b44 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UndefCapturedBlockVarChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UndefCapturedBlockVarChecker.cpp
@@ -19,6 +19,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp b/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp
index 216390a15c25d..0c3c4399b8dae 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedPointee.cpp
@@ -19,6 +19,7 @@
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicType.h"
+#include <optional>
 
 using namespace clang;
 using namespace clang::ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/UnreachableCodeChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UnreachableCodeChecker.cpp
index d231be64c2e19..032afb2b25d9a 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UnreachableCodeChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UnreachableCodeChecker.cpp
@@ -24,6 +24,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
 #include "llvm/ADT/SmallSet.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/VLASizeChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/VLASizeChecker.cpp
index cf519b085892d..11b3a371f2dc4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/VLASizeChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/VLASizeChecker.cpp
@@ -24,6 +24,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/VforkChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/VforkChecker.cpp
index 04e6603b4cbeb..d0d16af19514d 100644
--- a/clang/lib/StaticAnalyzer/Checkers/VforkChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/VforkChecker.cpp
@@ -35,6 +35,7 @@
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/AST/ParentMap.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
index 9c7a599717632..d2f4bdaeef1d4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/ExprCXX.h"
+#include <optional>
 
 using llvm::Optional;
 namespace clang {
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp
index 6b4615e189bcd..edd7a1e685a16 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp
@@ -19,6 +19,7 @@
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/Support/Casting.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.cpp
index 99c3523092b92..a7216e28eb093 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.cpp
@@ -13,6 +13,7 @@
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/ExprCXX.h"
 #include "llvm/ADT/Optional.h"
+#include <optional>
 
 using llvm::Optional;
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp
index fa9ece217cc06..754ca763de539 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp
@@ -14,6 +14,7 @@
 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp
index e6d0948f71bb9..cc4b08d5cb5f9 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp
@@ -19,6 +19,7 @@
 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "llvm/ADT/DenseSet.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
index 0c952b5ab9a54..dd95abb8ff30f 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
@@ -14,6 +14,7 @@
 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLocalVarsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLocalVarsChecker.cpp
index 7e86f28cb70ff..74468b02a9f8a 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLocalVarsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLocalVarsChecker.cpp
@@ -20,6 +20,7 @@
 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "llvm/ADT/DenseSet.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/Yaml.h b/clang/lib/StaticAnalyzer/Checkers/Yaml.h
index 6c9e525a44aa0..34840917ad49e 100644
--- a/clang/lib/StaticAnalyzer/Checkers/Yaml.h
+++ b/clang/lib/StaticAnalyzer/Checkers/Yaml.h
@@ -17,6 +17,7 @@
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Support/YAMLTraits.h"
+#include <optional>
 
 namespace clang {
 namespace ento {
diff --git a/clang/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp b/clang/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp
index f8e32b6769cfb..fb5da11e06941 100644
--- a/clang/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp
+++ b/clang/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <cstddef>
+#include <optional>
 #include <utility>
 #include <vector>
 
diff --git a/clang/lib/StaticAnalyzer/Core/BugReporter.cpp b/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
index 513de15cab699..64935dfdaee67 100644
--- a/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
@@ -65,6 +65,7 @@
 #include <cstddef>
 #include <iterator>
 #include <memory>
+#include <optional>
 #include <queue>
 #include <string>
 #include <tuple>
diff --git a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
index 01ba95a715cd7..5281b45510f5b 100644
--- a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
@@ -59,6 +59,7 @@
 #include <cassert>
 #include <deque>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/lib/StaticAnalyzer/Core/CallDescription.cpp b/clang/lib/StaticAnalyzer/Core/CallDescription.cpp
index 229fb4883ed29..38d80dfc51f44 100644
--- a/clang/lib/StaticAnalyzer/Core/CallDescription.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CallDescription.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include <iterator>
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Core/CallEvent.cpp b/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
index 8db57819dec23..cff2fde280a28 100644
--- a/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
@@ -61,6 +61,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
+#include <optional>
 #include <utility>
 
 #define DEBUG_TYPE "static-analyzer-call-event"
diff --git a/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp b/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp
index b6f2d782763f9..76d731b1c2dcc 100644
--- a/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp
@@ -14,6 +14,7 @@
 #include "clang/AST/Decl.h"
 #include "clang/AST/Expr.h"
 #include "clang/Lex/Preprocessor.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp b/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp
index 5227766a4a405..c23e3bc5f47df 100644
--- a/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp
@@ -28,6 +28,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormatVariadic.h"
 #include <cassert>
+#include <optional>
 #include <vector>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Core/CoreEngine.cpp b/clang/lib/StaticAnalyzer/Core/CoreEngine.cpp
index 994de60a732a2..8e15ef961d62f 100644
--- a/clang/lib/StaticAnalyzer/Core/CoreEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CoreEngine.cpp
@@ -34,6 +34,7 @@
 #include <algorithm>
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <utility>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
index 294572b7dbe41..23526d0d58f24 100644
--- a/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/Casting.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index de62e3781bbb9..1dc110230876a 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -78,6 +78,7 @@
 #include <cassert>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <utility>
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
index 10b70222af24b..397561f14e551 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
@@ -14,6 +14,7 @@
 #include "clang/AST/DeclCXX.h"
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
index 7139180e11a03..3bee6800d7360 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
@@ -20,6 +20,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
index d6968db31de9a..2db654506a204 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/SaveAndRestore.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
index 69599d1dc0db9..357d95c0848fe 100644
--- a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -17,6 +17,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/LoopUnrolling.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
index 0cd4ffb650894..1bd53ec698d06 100644
--- a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -51,6 +51,7 @@
 #include <cstdint>
 #include <functional>
 #include <iterator>
+#include <optional>
 #include <string>
 #include <tuple>
 #include <utility>
diff --git a/clang/lib/StaticAnalyzer/Core/PlistDiagnostics.cpp b/clang/lib/StaticAnalyzer/Core/PlistDiagnostics.cpp
index 56f441ec2c8f2..7fc53b172716e 100644
--- a/clang/lib/StaticAnalyzer/Core/PlistDiagnostics.cpp
+++ b/clang/lib/StaticAnalyzer/Core/PlistDiagnostics.cpp
@@ -28,6 +28,7 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/Casting.h"
 #include <memory>
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/ProgramState.cpp b/clang/lib/StaticAnalyzer/Core/ProgramState.cpp
index c3c9fc8d9ae6a..87ba432e7ba78 100644
--- a/clang/lib/StaticAnalyzer/Core/ProgramState.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ProgramState.cpp
@@ -19,6 +19,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index 91e71558314ad..22121708ddd3e 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <iterator>
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
index db8a5c5c38c84..91ac36f394e59 100644
--- a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -30,6 +30,7 @@
 #include "llvm/ADT/ImmutableMap.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <utility>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
index d30d844b20755..0affc6f9b9054 100644
--- a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
@@ -38,6 +38,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include <cassert>
+#include <optional>
 #include <tuple>
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Core/SVals.cpp b/clang/lib/StaticAnalyzer/Core/SVals.cpp
index 31725926cd0d0..ae2f3ff8efd34 100644
--- a/clang/lib/StaticAnalyzer/Core/SVals.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SVals.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
index dcb6043e9df3a..5c4eed90bc28e 100644
--- a/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
@@ -15,6 +15,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
+#include <optional>
 
 namespace clang {
 
diff --git a/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp b/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
index 77dd599343dfa..6f0abe56e6fd1 100644
--- a/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
@@ -15,6 +15,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SValVisitor.h"
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Core/Store.cpp b/clang/lib/StaticAnalyzer/Core/Store.cpp
index 9e64c67c9287b..37a3a6fd79e4d 100644
--- a/clang/lib/StaticAnalyzer/Core/Store.cpp
+++ b/clang/lib/StaticAnalyzer/Core/Store.cpp
@@ -35,6 +35,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
 #include <cstdint>
+#include <optional>
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/Tooling/ASTDiff/ASTDiff.cpp b/clang/lib/Tooling/ASTDiff/ASTDiff.cpp
index a25a7db28ae84..bfaa902042d20 100644
--- a/clang/lib/Tooling/ASTDiff/ASTDiff.cpp
+++ b/clang/lib/Tooling/ASTDiff/ASTDiff.cpp
@@ -19,6 +19,7 @@
 
 #include <limits>
 #include <memory>
+#include <optional>
 #include <unordered_set>
 
 using namespace llvm;
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
index 026bdfe03f28c..859497b8581bf 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -10,6 +10,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SmallVectorMemoryBuffer.h"
 #include "llvm/Support/Threading.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp
index 88540dd242cb4..70832f4b57cf4 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp
@@ -8,6 +8,7 @@
 
 #include "clang/Tooling/DependencyScanning/DependencyScanningTool.h"
 #include "clang/Frontend/Utils.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
index 5af355aaacb7b..957e0163f814d 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
@@ -23,6 +23,7 @@
 #include "clang/Tooling/DependencyScanning/ModuleDepCollector.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/Host.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
index 61191fcdf8d5e..a91157c4e2e4a 100644
--- a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
+++ b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
@@ -14,6 +14,7 @@
 #include "clang/Tooling/DependencyScanning/DependencyScanningWorker.h"
 #include "llvm/Support/BLAKE3.h"
 #include "llvm/Support/StringSaver.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp b/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp
index 665d67ea33c41..c7128f20c3ac0 100644
--- a/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp
+++ b/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp
@@ -13,6 +13,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Path.h"
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
index 5e424cc7cd77b..338797cc92ea6 100644
--- a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
+++ b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
@@ -58,6 +58,7 @@
 #include "llvm/Support/StringSaver.h"
 #include "llvm/Support/raw_ostream.h"
 #include <memory>
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/lib/Tooling/JSONCompilationDatabase.cpp b/clang/lib/Tooling/JSONCompilationDatabase.cpp
index 158b9a5473eac..cc5bd4a02b26d 100644
--- a/clang/lib/Tooling/JSONCompilationDatabase.cpp
+++ b/clang/lib/Tooling/JSONCompilationDatabase.cpp
@@ -34,6 +34,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <string>
 #include <system_error>
 #include <tuple>
diff --git a/clang/lib/Tooling/Refactoring/ASTSelection.cpp b/clang/lib/Tooling/Refactoring/ASTSelection.cpp
index 9658ce574197a..943d4ed49b78c 100644
--- a/clang/lib/Tooling/Refactoring/ASTSelection.cpp
+++ b/clang/lib/Tooling/Refactoring/ASTSelection.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/LexicallyOrderedRecursiveASTVisitor.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/Support/SaveAndRestore.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/lib/Tooling/Refactoring/ASTSelectionRequirements.cpp b/clang/lib/Tooling/Refactoring/ASTSelectionRequirements.cpp
index 70a4df07ea67b..e6a8e12e3697a 100644
--- a/clang/lib/Tooling/Refactoring/ASTSelectionRequirements.cpp
+++ b/clang/lib/Tooling/Refactoring/ASTSelectionRequirements.cpp
@@ -8,6 +8,7 @@
 
 #include "clang/Tooling/Refactoring/RefactoringActionRuleRequirements.h"
 #include "clang/AST/Attr.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/lib/Tooling/Refactoring/Extract/Extract.cpp b/clang/lib/Tooling/Refactoring/Extract/Extract.cpp
index 402b561090524..efd29fc75c820 100644
--- a/clang/lib/Tooling/Refactoring/Extract/Extract.cpp
+++ b/clang/lib/Tooling/Refactoring/Extract/Extract.cpp
@@ -19,6 +19,7 @@
 #include "clang/AST/ExprObjC.h"
 #include "clang/Rewrite/Core/Rewriter.h"
 #include "clang/Tooling/Refactoring/Extract/SourceExtraction.h"
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/lib/Tooling/Refactoring/Extract/SourceExtraction.cpp b/clang/lib/Tooling/Refactoring/Extract/SourceExtraction.cpp
index 5d57ecf90a96d..d4de57f6c1433 100644
--- a/clang/lib/Tooling/Refactoring/Extract/SourceExtraction.cpp
+++ b/clang/lib/Tooling/Refactoring/Extract/SourceExtraction.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/StmtObjC.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Lexer.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/lib/Tooling/Syntax/Tokens.cpp b/clang/lib/Tooling/Syntax/Tokens.cpp
index d0c82018f82bc..d99eda3efe13d 100644
--- a/clang/lib/Tooling/Syntax/Tokens.cpp
+++ b/clang/lib/Tooling/Syntax/Tokens.cpp
@@ -27,6 +27,7 @@
 #include <algorithm>
 #include <cassert>
 #include <iterator>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/lib/Tooling/Transformer/Parsing.cpp b/clang/lib/Tooling/Transformer/Parsing.cpp
index 57df92cd22989..dade27114d8a9 100644
--- a/clang/lib/Tooling/Transformer/Parsing.cpp
+++ b/clang/lib/Tooling/Transformer/Parsing.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp b/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp
index ebeef5dce1ebe..071923c9672f7 100644
--- a/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp
+++ b/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp
@@ -23,6 +23,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Signals.h"
+#include <optional>
 #include <sstream>
 #include <string>
 
diff --git a/clang/tools/clang-refactor/ClangRefactor.cpp b/clang/tools/clang-refactor/ClangRefactor.cpp
index 111144b295d83..e66bf6658877e 100644
--- a/clang/tools/clang-refactor/ClangRefactor.cpp
+++ b/clang/tools/clang-refactor/ClangRefactor.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 #include <string>
 
 using namespace clang;
diff --git a/clang/tools/clang-refactor/TestSupport.cpp b/clang/tools/clang-refactor/TestSupport.cpp
index 6e7e7d56b2c93..9736d1e0d880f 100644
--- a/clang/tools/clang-refactor/TestSupport.cpp
+++ b/clang/tools/clang-refactor/TestSupport.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace llvm;
 
diff --git a/clang/tools/clang-refactor/TestSupport.h b/clang/tools/clang-refactor/TestSupport.h
index c6b37b4cd6448..7ce1094d13c77 100644
--- a/clang/tools/clang-refactor/TestSupport.h
+++ b/clang/tools/clang-refactor/TestSupport.h
@@ -22,6 +22,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Error.h"
 #include <map>
+#include <optional>
 #include <string>
 
 namespace clang {
diff --git a/clang/tools/clang-repl/ClangRepl.cpp b/clang/tools/clang-repl/ClangRepl.cpp
index 8f661a57e9906..42b2452b77280 100644
--- a/clang/tools/clang-repl/ClangRepl.cpp
+++ b/clang/tools/clang-repl/ClangRepl.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Support/ManagedStatic.h" // llvm_shutdown
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TargetSelect.h" // llvm::Initialize*
+#include <optional>
 
 static llvm::cl::list<std::string>
     ClangArgs("Xcc",
diff --git a/clang/tools/clang-scan-deps/ClangScanDeps.cpp b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
index 51c7f37f93cd8..f8b915dd4389d 100644
--- a/clang/tools/clang-scan-deps/ClangScanDeps.cpp
+++ b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/ThreadPool.h"
 #include "llvm/Support/Threading.h"
 #include <mutex>
+#include <optional>
 #include <thread>
 
 using namespace clang;
diff --git a/clang/tools/diagtool/FindDiagnosticID.cpp b/clang/tools/diagtool/FindDiagnosticID.cpp
index 328ebff5ed24d..2e57a65e0e7a4 100644
--- a/clang/tools/diagtool/FindDiagnosticID.cpp
+++ b/clang/tools/diagtool/FindDiagnosticID.cpp
@@ -10,6 +10,7 @@
 #include "DiagnosticNames.h"
 #include "clang/Basic/AllDiagnostics.h"
 #include "llvm/Support/CommandLine.h"
+#include <optional>
 
 DEF_DIAGTOOL("find-diagnostic-id", "Print the id of the given diagnostic",
              FindDiagnosticID)
diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp
index b0fca509b0c66..2a87266cf92d4 100644
--- a/clang/tools/driver/cc1as_main.cpp
+++ b/clang/tools/driver/cc1as_main.cpp
@@ -54,6 +54,7 @@
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
 #include <memory>
+#include <optional>
 #include <system_error>
 using namespace clang;
 using namespace clang::driver;
diff --git a/clang/tools/driver/cc1gen_reproducer_main.cpp b/clang/tools/driver/cc1gen_reproducer_main.cpp
index d58e8fbed7cbb..08d518de14ca2 100644
--- a/clang/tools/driver/cc1gen_reproducer_main.cpp
+++ b/clang/tools/driver/cc1gen_reproducer_main.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index 07b7850ef72c6..536b4ab00af17 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -57,6 +57,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/thread.h"
 #include <mutex>
+#include <optional>
 
 #if LLVM_ENABLE_THREADS != 0 && defined(__APPLE__)
 #define USE_DARWIN_THREADS
diff --git a/clang/tools/libclang/CXType.cpp b/clang/tools/libclang/CXType.cpp
index 21a7724d7fdd5..f5534dc912d24 100644
--- a/clang/tools/libclang/CXType.cpp
+++ b/clang/tools/libclang/CXType.cpp
@@ -22,6 +22,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Basic/AddressSpaces.h"
 #include "clang/Frontend/ASTUnit.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/tools/libclang/CursorVisitor.h b/clang/tools/libclang/CursorVisitor.h
index 74190bd7f0152..b8a9d34ab6444 100644
--- a/clang/tools/libclang/CursorVisitor.h
+++ b/clang/tools/libclang/CursorVisitor.h
@@ -14,6 +14,7 @@
 #include "Index_Internal.h"
 #include "clang/AST/DeclVisitor.h"
 #include "clang/AST/TypeLocVisitor.h"
+#include <optional>
 
 namespace clang {
 class PreprocessingRecord;
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 865574f0fec6d..415cbc02d7f34 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -18,6 +18,7 @@
 #include "gtest/gtest.h"
 
 #include "ASTImporterFixtures.h"
+#include <optional>
 
 namespace clang {
 namespace ast_matchers {
diff --git a/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp b/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp
index 312456625c4bc..ac09b27efa5ec 100644
--- a/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp
+++ b/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp
@@ -11,6 +11,7 @@
 #include "clang/ASTMatchers/Dynamic/Registry.h"
 #include "llvm/ADT/Optional.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/clang/unittests/ASTMatchers/Dynamic/RegistryTest.cpp b/clang/unittests/ASTMatchers/Dynamic/RegistryTest.cpp
index 7c7d45ac565f8..dddd13bc6e457 100644
--- a/clang/unittests/ASTMatchers/Dynamic/RegistryTest.cpp
+++ b/clang/unittests/ASTMatchers/Dynamic/RegistryTest.cpp
@@ -9,6 +9,7 @@
 #include "../ASTMatchersTest.h"
 #include "clang/ASTMatchers/Dynamic/Registry.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <vector>
 
 namespace clang {
diff --git a/clang/unittests/Analysis/FlowSensitive/MultiVarConstantPropagationTest.cpp b/clang/unittests/Analysis/FlowSensitive/MultiVarConstantPropagationTest.cpp
index d454858e93482..8b5fc1fb2f11c 100644
--- a/clang/unittests/Analysis/FlowSensitive/MultiVarConstantPropagationTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/MultiVarConstantPropagationTest.cpp
@@ -34,6 +34,7 @@
 #include "gtest/gtest.h"
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <ostream>
 #include <string>
 #include <utility>
diff --git a/clang/unittests/Analysis/FlowSensitive/SingleVarConstantPropagationTest.cpp b/clang/unittests/Analysis/FlowSensitive/SingleVarConstantPropagationTest.cpp
index de99f01119012..62ea155f10ec7 100644
--- a/clang/unittests/Analysis/FlowSensitive/SingleVarConstantPropagationTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/SingleVarConstantPropagationTest.cpp
@@ -34,6 +34,7 @@
 #include "gtest/gtest.h"
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <ostream>
 #include <string>
 #include <utility>
diff --git a/clang/unittests/Analysis/FlowSensitive/TestingSupport.h b/clang/unittests/Analysis/FlowSensitive/TestingSupport.h
index 47fa108286907..97cebfcf2cd17 100644
--- a/clang/unittests/Analysis/FlowSensitive/TestingSupport.h
+++ b/clang/unittests/Analysis/FlowSensitive/TestingSupport.h
@@ -15,6 +15,7 @@
 
 #include <functional>
 #include <memory>
+#include <optional>
 #include <ostream>
 #include <string>
 #include <utility>
diff --git a/clang/unittests/Analysis/FlowSensitive/TransferBranchTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferBranchTest.cpp
index 9f3228d54ce11..4aadf75fe2586 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferBranchTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferBranchTest.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Testing/Annotations/Annotations.h"
 #include "llvm/Testing/Support/Error.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang::dataflow::test {
 namespace {
diff --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
index b4bf699b22918..95e53de61aa37 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 #include <utility>
 
diff --git a/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp b/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
index 31d51173d29b2..e03576ffb2eb8 100644
--- a/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
@@ -34,6 +34,7 @@
 #include "gtest/gtest.h"
 #include <cassert>
 #include <memory>
+#include <optional>
 #include <ostream>
 #include <string>
 #include <utility>
diff --git a/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp b/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp
index 51bb3aefd09df..e2abbbba2cb0a 100644
--- a/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/clang/unittests/Basic/DarwinSDKInfoTest.cpp b/clang/unittests/Basic/DarwinSDKInfoTest.cpp
index 887f74a97a58f..40c6c662f1d3f 100644
--- a/clang/unittests/Basic/DarwinSDKInfoTest.cpp
+++ b/clang/unittests/Basic/DarwinSDKInfoTest.cpp
@@ -9,6 +9,7 @@
 #include "clang/Basic/DarwinSDKInfo.h"
 #include "llvm/Support/JSON.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang/unittests/Basic/DiagnosticTest.cpp b/clang/unittests/Basic/DiagnosticTest.cpp
index 0ac931650e524..fd8042cf37340 100644
--- a/clang/unittests/Basic/DiagnosticTest.cpp
+++ b/clang/unittests/Basic/DiagnosticTest.cpp
@@ -10,6 +10,7 @@
 #include "clang/Basic/DiagnosticError.h"
 #include "clang/Basic/DiagnosticIDs.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang/unittests/Driver/SanitizerArgsTest.cpp b/clang/unittests/Driver/SanitizerArgsTest.cpp
index 8eecd53ef40c2..e9252ff2e5806 100644
--- a/clang/unittests/Driver/SanitizerArgsTest.cpp
+++ b/clang/unittests/Driver/SanitizerArgsTest.cpp
@@ -27,6 +27,7 @@
 #include "gtest/gtest.h"
 #include <cstdlib>
 #include <memory>
+#include <optional>
 #include <string>
 using namespace clang;
 using namespace clang::driver;
diff --git a/clang/unittests/Frontend/ParsedSourceLocationTest.cpp b/clang/unittests/Frontend/ParsedSourceLocationTest.cpp
index 1539005acd8fe..3e8f9e2e74990 100644
--- a/clang/unittests/Frontend/ParsedSourceLocationTest.cpp
+++ b/clang/unittests/Frontend/ParsedSourceLocationTest.cpp
@@ -8,6 +8,7 @@
 
 #include "clang/Frontend/CommandLineSourceLoc.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang/unittests/Lex/PPDependencyDirectivesTest.cpp b/clang/unittests/Lex/PPDependencyDirectivesTest.cpp
index 542fe73301cf0..840821a21d0be 100644
--- a/clang/unittests/Lex/PPDependencyDirectivesTest.cpp
+++ b/clang/unittests/Lex/PPDependencyDirectivesTest.cpp
@@ -21,6 +21,7 @@
 #include "clang/Lex/PreprocessorOptions.h"
 #include "llvm/Testing/Support/Error.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace clang;
 
diff --git a/clang/unittests/Serialization/SourceLocationEncodingTest.cpp b/clang/unittests/Serialization/SourceLocationEncodingTest.cpp
index f33a909a65335..d32e2429d9f64 100644
--- a/clang/unittests/Serialization/SourceLocationEncodingTest.cpp
+++ b/clang/unittests/Serialization/SourceLocationEncodingTest.cpp
@@ -10,6 +10,7 @@
 
 #include "gtest/gtest.h"
 #include <climits>
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang/unittests/StaticAnalyzer/TestReturnValueUnderConstruction.cpp b/clang/unittests/StaticAnalyzer/TestReturnValueUnderConstruction.cpp
index 6661b33f58344..c4a3cf122df8b 100644
--- a/clang/unittests/StaticAnalyzer/TestReturnValueUnderConstruction.cpp
+++ b/clang/unittests/StaticAnalyzer/TestReturnValueUnderConstruction.cpp
@@ -14,6 +14,7 @@
 #include "clang/StaticAnalyzer/Frontend/CheckerRegistry.h"
 #include "clang/Tooling/Tooling.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace ento {
diff --git a/clang/unittests/Tooling/ASTSelectionTest.cpp b/clang/unittests/Tooling/ASTSelectionTest.cpp
index 430562e9d2e0f..504d1051bf8c0 100644
--- a/clang/unittests/Tooling/ASTSelectionTest.cpp
+++ b/clang/unittests/Tooling/ASTSelectionTest.cpp
@@ -9,6 +9,7 @@
 #include "TestVisitor.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Tooling/Refactoring/ASTSelection.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/unittests/Tooling/RefactoringActionRulesTest.cpp b/clang/unittests/Tooling/RefactoringActionRulesTest.cpp
index b471cf207cff1..e80f75a931a07 100644
--- a/clang/unittests/Tooling/RefactoringActionRulesTest.cpp
+++ b/clang/unittests/Tooling/RefactoringActionRulesTest.cpp
@@ -16,6 +16,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/Errc.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/unittests/Tooling/RefactoringTest.cpp b/clang/unittests/Tooling/RefactoringTest.cpp
index c7a02e195d04a..2f3bd22ab4214 100644
--- a/clang/unittests/Tooling/RefactoringTest.cpp
+++ b/clang/unittests/Tooling/RefactoringTest.cpp
@@ -29,6 +29,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 namespace clang {
 namespace tooling {
diff --git a/clang/unittests/Tooling/SourceCodeBuildersTest.cpp b/clang/unittests/Tooling/SourceCodeBuildersTest.cpp
index 647ead4c77f0e..6db3031187c39 100644
--- a/clang/unittests/Tooling/SourceCodeBuildersTest.cpp
+++ b/clang/unittests/Tooling/SourceCodeBuildersTest.cpp
@@ -14,6 +14,7 @@
 #include "llvm/Testing/Support/SupportHelpers.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/unittests/Tooling/StencilTest.cpp b/clang/unittests/Tooling/StencilTest.cpp
index ee77933c428df..68d3a6c36583b 100644
--- a/clang/unittests/Tooling/StencilTest.cpp
+++ b/clang/unittests/Tooling/StencilTest.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Testing/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace clang;
 using namespace transformer;
diff --git a/clang/unittests/Tooling/Syntax/TokensTest.cpp b/clang/unittests/Tooling/Syntax/TokensTest.cpp
index 1c9cec86eb9c5..8f150463d805d 100644
--- a/clang/unittests/Tooling/Syntax/TokensTest.cpp
+++ b/clang/unittests/Tooling/Syntax/TokensTest.cpp
@@ -44,6 +44,7 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 #include <memory>
+#include <optional>
 #include <ostream>
 #include <string>
 
diff --git a/clang/unittests/Tooling/TransformerTest.cpp b/clang/unittests/Tooling/TransformerTest.cpp
index 4d5e22d944988..8d10f388b4acc 100644
--- a/clang/unittests/Tooling/TransformerTest.cpp
+++ b/clang/unittests/Tooling/TransformerTest.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <optional>
 
 using namespace clang;
 using namespace tooling;
diff --git a/clang/utils/TableGen/ASTTableGen.cpp b/clang/utils/TableGen/ASTTableGen.cpp
index 6aa8b28a942f3..79383bf92a1a9 100644
--- a/clang/utils/TableGen/ASTTableGen.cpp
+++ b/clang/utils/TableGen/ASTTableGen.cpp
@@ -15,6 +15,7 @@
 #include "ASTTableGen.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/Error.h"
+#include <optional>
 
 using namespace llvm;
 using namespace clang;
diff --git a/clang/utils/TableGen/ASTTableGen.h b/clang/utils/TableGen/ASTTableGen.h
index ab9429f3feee0..41f78a6a3bbcd 100644
--- a/clang/utils/TableGen/ASTTableGen.h
+++ b/clang/utils/TableGen/ASTTableGen.h
@@ -11,6 +11,7 @@
 
 #include "llvm/TableGen/Record.h"
 #include "llvm/ADT/STLExtras.h"
+#include <optional>
 
 // These are spellings in the tblgen files.
 
diff --git a/clang/utils/TableGen/ClangASTPropertiesEmitter.cpp b/clang/utils/TableGen/ClangASTPropertiesEmitter.cpp
index c3735f70136dd..3401e03ba7903 100644
--- a/clang/utils/TableGen/ClangASTPropertiesEmitter.cpp
+++ b/clang/utils/TableGen/ClangASTPropertiesEmitter.cpp
@@ -20,6 +20,7 @@
 #include "llvm/TableGen/TableGenBackend.h"
 #include <cctype>
 #include <map>
+#include <optional>
 #include <set>
 #include <string>
 using namespace llvm;
diff --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp
index 3ae1813d5d734..a261cf245100c 100644
--- a/clang/utils/TableGen/ClangAttrEmitter.cpp
+++ b/clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -37,6 +37,7 @@
 #include <cstdint>
 #include <map>
 #include <memory>
+#include <optional>
 #include <set>
 #include <sstream>
 #include <string>