diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/PathConfig.cpp b/clang-tools-extra/clang-include-fixer/find-all-symbols/PathConfig.cpp
index c12e4cf6cd416d..503fd60cb4c1b8 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/PathConfig.cpp
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/PathConfig.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "PathConfig.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Path.h"
 
 namespace clang {
diff --git a/clang/include/clang/Basic/Diagnostic.h b/clang/include/clang/Basic/Diagnostic.h
index c55b180487728c..9cc94c38e60d17 100644
--- a/clang/include/clang/Basic/Diagnostic.h
+++ b/clang/include/clang/Basic/Diagnostic.h
@@ -26,7 +26,6 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Compiler.h"
-#include "llvm/Support/Error.h"
 #include <cassert>
 #include <cstdint>
 #include <limits>
@@ -38,6 +37,10 @@
 #include <utility>
 #include <vector>
 
+namespace llvm {
+class Error;
+}
+
 namespace clang {
 
 class DeclContext;
@@ -1329,11 +1332,8 @@ inline DiagnosticBuilder DiagnosticsEngine::Report(SourceLocation Loc,
   return DiagnosticBuilder(this);
 }
 
-inline const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB,
-                                           llvm::Error &&E) {
-  DB.AddString(toString(std::move(E)));
-  return DB;
-}
+const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB,
+                                    llvm::Error &&E);
 
 inline DiagnosticBuilder DiagnosticsEngine::Report(unsigned DiagID) {
   return Report(SourceLocation(), DiagID);
diff --git a/clang/include/clang/Tooling/Refactoring/ASTSelection.h b/clang/include/clang/Tooling/Refactoring/ASTSelection.h
index a992d0f5adf193..239be36012c3d9 100644
--- a/clang/include/clang/Tooling/Refactoring/ASTSelection.h
+++ b/clang/include/clang/Tooling/Refactoring/ASTSelection.h
@@ -13,6 +13,7 @@
 #include "clang/AST/Stmt.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
+#include "llvm/Support/raw_ostream.h"
 #include <vector>
 
 namespace clang {
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 35232bebbb3a1e..9ebde22f7a587f 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -54,6 +54,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallBitVector.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstring>
diff --git a/clang/lib/AST/Interp/Disasm.cpp b/clang/lib/AST/Interp/Disasm.cpp
index e77a825eb1f237..293fdd4b3256e2 100644
--- a/clang/lib/AST/Interp/Disasm.cpp
+++ b/clang/lib/AST/Interp/Disasm.cpp
@@ -16,6 +16,7 @@
 #include "Program.h"
 #include "clang/AST/DeclCXX.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/Format.h"
 
 using namespace clang;
 using namespace clang::interp;
diff --git a/clang/lib/Basic/Diagnostic.cpp b/clang/lib/Basic/Diagnostic.cpp
index f258b37f2fa6ed..661eabf9bc7cbb 100644
--- a/clang/lib/Basic/Diagnostic.cpp
+++ b/clang/lib/Basic/Diagnostic.cpp
@@ -61,6 +61,12 @@ const DiagnosticBuilder &clang::operator<<(const DiagnosticBuilder &DB,
   return DB;
 }
 
+const DiagnosticBuilder &clang::operator<<(const DiagnosticBuilder &DB,
+                                           llvm::Error &&E) {
+  DB.AddString(toString(std::move(E)));
+  return DB;
+}
+
 static void DummyArgToStringFn(DiagnosticsEngine::ArgumentKind AK, intptr_t QT,
                             StringRef Modifier, StringRef Argument,
                             ArrayRef<DiagnosticsEngine::ArgumentValue> PrevArgs,
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index 9a852141c6eea1..0251b0dc80ae21 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -25,6 +25,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/ConvertUTF.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
diff --git a/clang/lib/Sema/CodeCompleteConsumer.cpp b/clang/lib/Sema/CodeCompleteConsumer.cpp
index 2402d896faac24..f1ad8aeaacbb0b 100644
--- a/clang/lib/Sema/CodeCompleteConsumer.cpp
+++ b/clang/lib/Sema/CodeCompleteConsumer.cpp
@@ -23,6 +23,7 @@
 #include "clang/Sema/Sema.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/Casting.h"
diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
index dcad2264e8cd9c..4558b6936e7fb4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -23,6 +23,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp
index 78c51f3eab0109..fc35082705fa64 100644
--- a/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp
@@ -90,6 +90,7 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
+#include "llvm/ADT/StringExtras.h"
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/NonNullParamChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/NonNullParamChecker.cpp
index 8c7975a513a070..1bff681fb0d086 100644
--- a/clang/lib/StaticAnalyzer/Checkers/NonNullParamChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/NonNullParamChecker.cpp
@@ -21,6 +21,7 @@
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "llvm/ADT/StringExtras.h"
 
 using namespace clang;
 using namespace ento;
diff --git a/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
index 6ea8451512f3aa..381334de068e34 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
@@ -20,6 +20,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace clang;
diff --git a/clang/lib/StaticAnalyzer/Core/BugReporter.cpp b/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
index 1864bcef9b8733..0848d6a6ec61fb 100644
--- a/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
@@ -51,6 +51,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Casting.h"
diff --git a/clang/lib/Tooling/Transformer/SourceCode.cpp b/clang/lib/Tooling/Transformer/SourceCode.cpp
index 0530b3fa0e9591..a29d2e796d9481 100644
--- a/clang/lib/Tooling/Transformer/SourceCode.cpp
+++ b/clang/lib/Tooling/Transformer/SourceCode.cpp
@@ -20,6 +20,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
 #include <set>
 
 using namespace clang;