diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -211,7 +211,7 @@
   mutable SmallVector<Type *, 0> Types;
   mutable llvm::FoldingSet<ExtQuals> ExtQualNodes;
   mutable llvm::FoldingSet<ComplexType> ComplexTypes;
-  mutable llvm::FoldingSet<PointerType> PointerTypes;
+  mutable llvm::FoldingSet<PointerType> PointerTypes{GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<AdjustedType> AdjustedTypes;
   mutable llvm::FoldingSet<BlockPointerType> BlockPointerTypes;
   mutable llvm::FoldingSet<LValueReferenceType> LValueReferenceTypes;
@@ -243,9 +243,10 @@
     SubstTemplateTypeParmPackTypes;
   mutable llvm::ContextualFoldingSet<TemplateSpecializationType, ASTContext&>
     TemplateSpecializationTypes;
-  mutable llvm::FoldingSet<ParenType> ParenTypes;
+  mutable llvm::FoldingSet<ParenType> ParenTypes{GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<UsingType> UsingTypes;
-  mutable llvm::FoldingSet<ElaboratedType> ElaboratedTypes;
+  mutable llvm::FoldingSet<ElaboratedType> ElaboratedTypes{
+      GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<DependentNameType> DependentNameTypes;
   mutable llvm::ContextualFoldingSet<DependentTemplateSpecializationType,
                                      ASTContext&>
@@ -466,6 +467,10 @@
   };
   llvm::DenseMap<Module*, PerModuleInitializers*> ModuleInitializers;
 
+  static constexpr unsigned ConstantArrayTypesLog2InitSize = 8;
+  static constexpr unsigned GeneralTypesLog2InitSize = 9;
+  static constexpr unsigned FunctionProtoTypesLog2InitSize = 12;
+
   ASTContext &this_() { return *this; }
 
 public:
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -973,7 +973,8 @@
 ASTContext::ASTContext(LangOptions &LOpts, SourceManager &SM,
                        IdentifierTable &idents, SelectorTable &sels,
                        Builtin::Context &builtins, TranslationUnitKind TUKind)
-    : ConstantArrayTypes(this_()), FunctionProtoTypes(this_()),
+    : ConstantArrayTypes(this_(), ConstantArrayTypesLog2InitSize),
+      FunctionProtoTypes(this_(), FunctionProtoTypesLog2InitSize),
       TemplateSpecializationTypes(this_()),
       DependentTemplateSpecializationTypes(this_()), AutoTypes(this_()),
       SubstTemplateTemplateParmPacks(this_()),
diff --git a/clang/lib/CodeGen/CodeGenTypes.h b/clang/lib/CodeGen/CodeGenTypes.h
--- a/clang/lib/CodeGen/CodeGenTypes.h
+++ b/clang/lib/CodeGen/CodeGenTypes.h
@@ -76,7 +76,7 @@
   llvm::DenseMap<const Type*, llvm::StructType *> RecordDeclTypes;
 
   /// Hold memoized CGFunctionInfo results.
-  llvm::FoldingSet<CGFunctionInfo> FunctionInfos;
+  llvm::FoldingSet<CGFunctionInfo> FunctionInfos{FunctionInfosLog2InitSize};
 
   /// This set keeps track of records that we're currently converting
   /// to an IR type.  For example, when converting:
@@ -98,6 +98,7 @@
 
   llvm::SmallSet<const Type *, 8> RecordsWithOpaqueMemberPointers;
 
+  static constexpr unsigned FunctionInfosLog2InitSize = 9;
   /// Helper for ConvertType.
   llvm::Type *ConvertFunctionTypeInternal(QualType FT);