Index: clang/include/clang/AST/ASTContext.h
===================================================================
--- clang/include/clang/AST/ASTContext.h
+++ clang/include/clang/AST/ASTContext.h
@@ -407,7 +407,7 @@
   /// \brief Mapping from each declaration context to its corresponding
   /// mangling numbering context (used for constructs like lambdas which
   /// need to be consistently numbered for the mangler).
-  llvm::DenseMap<const DeclContext *, MangleNumberingContext *>
+  llvm::DenseMap<const DeclContext *, std::unique_ptr<MangleNumberingContext>>
       MangleNumberingContexts;
 
   /// \brief Side-table of mangling numbers for declarations which rarely
@@ -2470,7 +2470,7 @@
   /// DeclContext.
   MangleNumberingContext &getManglingNumberContext(const DeclContext *DC);
 
-  MangleNumberingContext *createMangleNumberingContext() const;
+  std::unique_ptr<MangleNumberingContext> createMangleNumberingContext() const;
 
   /// \brief Used by ParmVarDecl to store on the side the
   /// index of the parameter when it exceeds the size of the normal bitfield.
Index: clang/include/clang/AST/MangleNumberingContext.h
===================================================================
--- clang/include/clang/AST/MangleNumberingContext.h
+++ clang/include/clang/AST/MangleNumberingContext.h
@@ -29,7 +29,7 @@
 
 /// \brief Keeps track of the mangled names of lambda expressions and block
 /// literals within a particular context.
-class MangleNumberingContext : public RefCountedBase<MangleNumberingContext> {
+class MangleNumberingContext {
 public:
   virtual ~MangleNumberingContext() {}
 
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -876,7 +876,7 @@
     ///
     /// This mangling information is allocated lazily, since most contexts
     /// do not have lambda expressions or block literals.
-    IntrusiveRefCntPtr<MangleNumberingContext> MangleNumbering;
+    std::unique_ptr<MangleNumberingContext> MangleNumbering;
 
     /// \brief If we are processing a decltype type, a set of call expressions
     /// for which we have deferred checking the completeness of the return type.
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -794,8 +794,6 @@
 
   for (const auto &Value : ModuleInitializers)
     Value.second->~PerModuleInitializers();
-
-  llvm::DeleteContainerSeconds(MangleNumberingContexts);
 }
 
 void ASTContext::ReleaseParentMapEntries() {
@@ -8982,13 +8980,14 @@
 MangleNumberingContext &
 ASTContext::getManglingNumberContext(const DeclContext *DC) {
   assert(LangOpts.CPlusPlus);  // We don't need mangling numbers for plain C.
-  MangleNumberingContext *&MCtx = MangleNumberingContexts[DC];
+  std::unique_ptr<MangleNumberingContext> &MCtx = MangleNumberingContexts[DC];
   if (!MCtx)
     MCtx = createMangleNumberingContext();
   return *MCtx;
 }
 
-MangleNumberingContext *ASTContext::createMangleNumberingContext() const {
+std::unique_ptr<MangleNumberingContext>
+ASTContext::createMangleNumberingContext() const {
   return ABI->createMangleNumberingContext();
 }
 
Index: clang/lib/AST/CXXABI.h
===================================================================
--- clang/lib/AST/CXXABI.h
+++ clang/lib/AST/CXXABI.h
@@ -43,7 +43,8 @@
   virtual bool isNearlyEmpty(const CXXRecordDecl *RD) const = 0;
 
   /// Returns a new mangling number context for this C++ ABI.
-  virtual MangleNumberingContext *createMangleNumberingContext() const = 0;
+  virtual std::unique_ptr<MangleNumberingContext>
+  createMangleNumberingContext() const = 0;
 
   /// Adds a mapping from class to copy constructor for this C++ ABI.
   virtual void addCopyConstructorForExceptionObject(CXXRecordDecl *,
Index: clang/lib/AST/ItaniumCXXABI.cpp
===================================================================
--- clang/lib/AST/ItaniumCXXABI.cpp
+++ clang/lib/AST/ItaniumCXXABI.cpp
@@ -163,8 +163,9 @@
     return nullptr;
   }
 
-  MangleNumberingContext *createMangleNumberingContext() const override {
-    return new ItaniumNumberingContext();
+  std::unique_ptr<MangleNumberingContext>
+  createMangleNumberingContext() const override {
+    return llvm::make_unique<ItaniumNumberingContext>();
   }
 };
 }
Index: clang/lib/AST/MicrosoftCXXABI.cpp
===================================================================
--- clang/lib/AST/MicrosoftCXXABI.cpp
+++ clang/lib/AST/MicrosoftCXXABI.cpp
@@ -143,8 +143,9 @@
         const_cast<TagDecl *>(TD->getCanonicalDecl()));
   }
 
-  MangleNumberingContext *createMangleNumberingContext() const override {
-    return new MicrosoftNumberingContext();
+  std::unique_ptr<MangleNumberingContext>
+  createMangleNumberingContext() const override {
+    return llvm::make_unique<MicrosoftNumberingContext>();
   }
 };
 }