diff --git a/clang/include/clang/AST/DeclarationName.h b/clang/include/clang/AST/DeclarationName.h
index 82f6868e3a7e1a..a037e8b197bc35 100644
--- a/clang/include/clang/AST/DeclarationName.h
+++ b/clang/include/clang/AST/DeclarationName.h
@@ -857,6 +857,16 @@ struct DenseMapInfo<clang::DeclarationName> {
   }
 };
 
+template <> struct PointerLikeTypeTraits<clang::DeclarationName> {
+  static inline void *getAsVoidPointer(clang::DeclarationName P) {
+    return P.getAsOpaquePtr();
+  }
+  static inline clang::DeclarationName getFromVoidPointer(void *P) {
+    return clang::DeclarationName::getFromOpaquePtr(P);
+  }
+  static constexpr int NumLowBitsAvailable = 0;
+};
+
 } // namespace llvm
 
 // The definition of AssumedTemplateStorage is factored out of TemplateName to
diff --git a/clang/include/clang/AST/Redeclarable.h b/clang/include/clang/AST/Redeclarable.h
index 0975773dd2cb57..87252337a0f4b5 100644
--- a/clang/include/clang/AST/Redeclarable.h
+++ b/clang/include/clang/AST/Redeclarable.h
@@ -370,6 +370,7 @@ template <typename decl_type> class CanonicalDeclPtr {
 
 private:
   friend struct llvm::DenseMapInfo<CanonicalDeclPtr<decl_type>>;
+  friend struct llvm::PointerLikeTypeTraits<CanonicalDeclPtr<decl_type>>;
 
   decl_type *Ptr = nullptr;
 };
@@ -407,6 +408,20 @@ struct DenseMapInfo<clang::CanonicalDeclPtr<decl_type>> {
   }
 };
 
+template <typename decl_type>
+struct PointerLikeTypeTraits<clang::CanonicalDeclPtr<decl_type>> {
+  static inline void *getAsVoidPointer(clang::CanonicalDeclPtr<decl_type> P) {
+    return P.Ptr;
+  }
+  static inline clang::CanonicalDeclPtr<decl_type> getFromVoidPointer(void *P) {
+    clang::CanonicalDeclPtr<decl_type> C;
+    C.Ptr = PointerLikeTypeTraits<decl_type *>::getFromVoidPtr(P);
+    return C;
+  }
+  static constexpr int NumLowBitsAvailable =
+      PointerLikeTypeTraits<decl_type *>::NumLowBitsAvailable;
+};
+
 } // namespace llvm
 
 #endif // LLVM_CLANG_AST_REDECLARABLE_H
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 2f2b52106f3d47..735349c3de6266 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -42,7 +42,7 @@
 #include "clang/Sema/TemplateInstCallback.h"
 #include "clang/Sema/TypoCorrection.h"
 #include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Support/TimeProfiler.h"
 
 using namespace clang;
@@ -1490,7 +1490,7 @@ class DeferredDiagnosticsEmitter
   typedef UsedDeclVisitor<DeferredDiagnosticsEmitter> Inherited;
 
   // Whether the function is already in the current use-path.
-  llvm::SmallSet<CanonicalDeclPtr<Decl>, 4> InUsePath;
+  llvm::SmallPtrSet<CanonicalDeclPtr<Decl>, 4> InUsePath;
 
   // The current use-path.
   llvm::SmallVector<CanonicalDeclPtr<FunctionDecl>, 4> UsePath;
@@ -1499,7 +1499,7 @@ class DeferredDiagnosticsEmitter
   // case not in OpenMP device context. Done[1] is for the case in OpenMP
   // device context. We need two sets because diagnostics emission may be
   // different depending on whether it is in OpenMP device context.
-  llvm::SmallSet<CanonicalDeclPtr<Decl>, 4> DoneMap[2];
+  llvm::SmallPtrSet<CanonicalDeclPtr<Decl>, 4> DoneMap[2];
 
   // Emission state of the root node of the current use graph.
   bool ShouldEmitRootNode;
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 212f5e4746d603..001fabff96ff25 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -172,7 +172,7 @@ ParsedType Sema::getDestructorName(SourceLocation TildeLoc,
   bool Failed = false;
 
   llvm::SmallVector<NamedDecl*, 8> FoundDecls;
-  llvm::SmallSet<CanonicalDeclPtr<Decl>, 8> FoundDeclSet;
+  llvm::SmallPtrSet<CanonicalDeclPtr<Decl>, 8> FoundDeclSet;
 
   // If we have an object type, it's because we are in a
   // pseudo-destructor-expression or a member access expression, and
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 8bf605e5e76b8f..1e7d432217d5da 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -19028,7 +19028,7 @@ OMPClause *Sema::ActOnOpenMPUsesAllocatorClause(
           [](const UsesAllocatorsData &D) { return D.AllocatorTraits; }) &&
       !findOMPAlloctraitT(*this, StartLoc, DSAStack))
     return nullptr;
-  llvm::SmallSet<CanonicalDeclPtr<Decl>, 4> PredefinedAllocators;
+  llvm::SmallPtrSet<CanonicalDeclPtr<Decl>, 4> PredefinedAllocators;
   for (int I = 0; I < OMPAllocateDeclAttr::OMPUserDefinedMemAlloc; ++I) {
     auto AllocatorKind = static_cast<OMPAllocateDeclAttr::AllocatorTypeTy>(I);
     StringRef Allocator =
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 2345a12caeb2e8..a8803aeb1b8aba 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -81,7 +81,7 @@
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/ScopeExit.h"
-#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
@@ -3690,7 +3690,7 @@ ASTWriter::GenerateNameLookupTable(const DeclContext *ConstDC,
 
   // We also build up small sets of the constructor and conversion function
   // names which are visible.
-  llvm::SmallSet<DeclarationName, 8> ConstructorNameSet, ConversionNameSet;
+  llvm::SmallPtrSet<DeclarationName, 8> ConstructorNameSet, ConversionNameSet;
 
   for (auto &Lookup : *DC->buildLookup()) {
     auto &Name = Lookup.first;
diff --git a/clang/lib/StaticAnalyzer/Checkers/ObjCMissingSuperCallChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ObjCMissingSuperCallChecker.cpp
index 24e2a4dea922e6..35a600f2d7b866 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ObjCMissingSuperCallChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ObjCMissingSuperCallChecker.cpp
@@ -21,7 +21,7 @@
 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
-#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -74,7 +74,7 @@ class ObjCSuperCallChecker : public Checker<
   void initializeSelectors(ASTContext &Ctx) const;
   void fillSelectors(ASTContext &Ctx, ArrayRef<SelectorDescriptor> Sel,
                      StringRef ClassName) const;
-  mutable llvm::StringMap<llvm::SmallSet<Selector, 16> > SelectorsForClass;
+  mutable llvm::StringMap<llvm::SmallPtrSet<Selector, 16>> SelectorsForClass;
   mutable bool IsInitialized;
 };
 
@@ -100,7 +100,8 @@ bool ObjCSuperCallChecker::isCheckableClass(const ObjCImplementationDecl *D,
 void ObjCSuperCallChecker::fillSelectors(ASTContext &Ctx,
                                          ArrayRef<SelectorDescriptor> Sel,
                                          StringRef ClassName) const {
-  llvm::SmallSet<Selector, 16> &ClassSelectors = SelectorsForClass[ClassName];
+  llvm::SmallPtrSet<Selector, 16> &ClassSelectors =
+      SelectorsForClass[ClassName];
   // Fill the Selectors SmallSet with all selectors we want to check.
   for (ArrayRef<SelectorDescriptor>::iterator I = Sel.begin(), E = Sel.end();
        I != E; ++I) {