diff --git a/clang-tools-extra/clang-doc/BitcodeReader.cpp b/clang-tools-extra/clang-doc/BitcodeReader.cpp
index 9ac60fa73a782..8c97186b299fc 100644
--- a/clang-tools-extra/clang-doc/BitcodeReader.cpp
+++ b/clang-tools-extra/clang-doc/BitcodeReader.cpp
@@ -67,13 +67,13 @@ llvm::Error decodeRecord(const Record &R, AccessSpecifier &Field,
 
 llvm::Error decodeRecord(const Record &R, TagTypeKind &Field,
                          llvm::StringRef Blob) {
-  switch (R[0]) {
-  case TTK_Struct:
-  case TTK_Interface:
-  case TTK_Union:
-  case TTK_Class:
-  case TTK_Enum:
-    Field = (TagTypeKind)R[0];
+  switch (static_cast<TagTypeKind>(R[0])) {
+  case TagTypeKind::Struct:
+  case TagTypeKind::Interface:
+  case TagTypeKind::Union:
+  case TagTypeKind::Class:
+  case TagTypeKind::Enum:
+    Field = static_cast<TagTypeKind>(R[0]);
     return llvm::Error::success();
   default:
     return llvm::createStringError(llvm::inconvertibleErrorCode(),
diff --git a/clang-tools-extra/clang-doc/BitcodeWriter.cpp b/clang-tools-extra/clang-doc/BitcodeWriter.cpp
index 2ece99a3124ab..7e5a11783d303 100644
--- a/clang-tools-extra/clang-doc/BitcodeWriter.cpp
+++ b/clang-tools-extra/clang-doc/BitcodeWriter.cpp
@@ -551,7 +551,7 @@ void ClangDocBitcodeWriter::emitBlock(const RecordInfo &I) {
     emitRecord(*I.DefLoc, RECORD_DEFLOCATION);
   for (const auto &L : I.Loc)
     emitRecord(L, RECORD_LOCATION);
-  emitRecord(I.TagType, RECORD_TAG_TYPE);
+  emitRecord(llvm::to_underlying(I.TagType), RECORD_TAG_TYPE);
   emitRecord(I.IsTypeDef, RECORD_IS_TYPE_DEF);
   for (const auto &N : I.Members)
     emitBlock(N);
@@ -578,7 +578,7 @@ void ClangDocBitcodeWriter::emitBlock(const BaseRecordInfo &I) {
   emitRecord(I.USR, BASE_RECORD_USR);
   emitRecord(I.Name, BASE_RECORD_NAME);
   emitRecord(I.Path, BASE_RECORD_PATH);
-  emitRecord(I.TagType, BASE_RECORD_TAG_TYPE);
+  emitRecord(llvm::to_underlying(I.TagType), BASE_RECORD_TAG_TYPE);
   emitRecord(I.IsVirtual, BASE_RECORD_IS_VIRTUAL);
   emitRecord(I.Access, BASE_RECORD_ACCESS);
   emitRecord(I.IsParent, BASE_RECORD_IS_PARENT);
diff --git a/clang-tools-extra/clang-doc/Generators.cpp b/clang-tools-extra/clang-doc/Generators.cpp
index da19c05ab67b9..a3986b66f3c74 100644
--- a/clang-tools-extra/clang-doc/Generators.cpp
+++ b/clang-tools-extra/clang-doc/Generators.cpp
@@ -28,15 +28,15 @@ findGeneratorByName(llvm::StringRef Format) {
 
 std::string getTagType(TagTypeKind AS) {
   switch (AS) {
-  case TagTypeKind::TTK_Class:
+  case TagTypeKind::Class:
     return "class";
-  case TagTypeKind::TTK_Union:
+  case TagTypeKind::Union:
     return "union";
-  case TagTypeKind::TTK_Interface:
+  case TagTypeKind::Interface:
     return "interface";
-  case TagTypeKind::TTK_Struct:
+  case TagTypeKind::Struct:
     return "struct";
-  case TagTypeKind::TTK_Enum:
+  case TagTypeKind::Enum:
     return "enum";
   }
   llvm_unreachable("Unknown TagTypeKind");
diff --git a/clang-tools-extra/clang-doc/Representation.cpp b/clang-tools-extra/clang-doc/Representation.cpp
index 3d078d575a127..7dcf646322e6f 100644
--- a/clang-tools-extra/clang-doc/Representation.cpp
+++ b/clang-tools-extra/clang-doc/Representation.cpp
@@ -239,7 +239,7 @@ RecordInfo::RecordInfo(SymbolID USR, StringRef Name, StringRef Path)
 
 void RecordInfo::merge(RecordInfo &&Other) {
   assert(mergeable(Other));
-  if (!TagType)
+  if (!llvm::to_underlying(TagType))
     TagType = Other.TagType;
   IsTypeDef = IsTypeDef || Other.IsTypeDef;
   if (Members.empty())
diff --git a/clang-tools-extra/clang-doc/Representation.h b/clang-tools-extra/clang-doc/Representation.h
index aa5fa7f07083e..a6b144eb7fa2a 100644
--- a/clang-tools-extra/clang-doc/Representation.h
+++ b/clang-tools-extra/clang-doc/Representation.h
@@ -350,7 +350,7 @@ struct RecordInfo : public SymbolInfo {
   void merge(RecordInfo &&I);
 
   // Type of this record (struct, class, union, interface).
-  TagTypeKind TagType = TagTypeKind::TTK_Struct;
+  TagTypeKind TagType = TagTypeKind::Struct;
 
   // Full qualified name of this record, including namespaces and template
   // specializations.
diff --git a/clang-tools-extra/clang-doc/YAMLGenerator.cpp b/clang-tools-extra/clang-doc/YAMLGenerator.cpp
index 57cb294e0ab69..b612380a3cfa7 100644
--- a/clang-tools-extra/clang-doc/YAMLGenerator.cpp
+++ b/clang-tools-extra/clang-doc/YAMLGenerator.cpp
@@ -47,11 +47,11 @@ template <> struct ScalarEnumerationTraits<clang::AccessSpecifier> {
 
 template <> struct ScalarEnumerationTraits<clang::TagTypeKind> {
   static void enumeration(IO &IO, clang::TagTypeKind &Value) {
-    IO.enumCase(Value, "Struct", clang::TagTypeKind::TTK_Struct);
-    IO.enumCase(Value, "Interface", clang::TagTypeKind::TTK_Interface);
-    IO.enumCase(Value, "Union", clang::TagTypeKind::TTK_Union);
-    IO.enumCase(Value, "Class", clang::TagTypeKind::TTK_Class);
-    IO.enumCase(Value, "Enum", clang::TagTypeKind::TTK_Enum);
+    IO.enumCase(Value, "Struct", clang::TagTypeKind::Struct);
+    IO.enumCase(Value, "Interface", clang::TagTypeKind::Interface);
+    IO.enumCase(Value, "Union", clang::TagTypeKind::Union);
+    IO.enumCase(Value, "Class", clang::TagTypeKind::Class);
+    IO.enumCase(Value, "Enum", clang::TagTypeKind::Enum);
   }
 };
 
diff --git a/clang-tools-extra/clangd/refactor/InsertionPoint.cpp b/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
index 4b04021a5bd46..e3b11ceb4f016 100644
--- a/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
+++ b/clang-tools-extra/clangd/refactor/InsertionPoint.cpp
@@ -85,7 +85,8 @@ SourceLocation endLoc(const DeclContext &DC) {
 }
 
 AccessSpecifier getAccessAtEnd(const CXXRecordDecl &C) {
-  AccessSpecifier Spec = (C.getTagKind() == TTK_Class ? AS_private : AS_public);
+  AccessSpecifier Spec =
+      (C.getTagKind() == TagTypeKind::Class ? AS_private : AS_public);
   for (const auto *D : C.decls())
     if (const auto *ASD = llvm::dyn_cast<AccessSpecDecl>(D))
       Spec = ASD->getAccess();
diff --git a/clang-tools-extra/unittests/clang-doc/BitcodeTest.cpp b/clang-tools-extra/unittests/clang-doc/BitcodeTest.cpp
index 53e84b1814453..5b9745af7810a 100644
--- a/clang-tools-extra/unittests/clang-doc/BitcodeTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/BitcodeTest.cpp
@@ -81,7 +81,7 @@ TEST(BitcodeTest, emitRecordInfoBitcode) {
   I.Loc.emplace_back(12, llvm::SmallString<16>{"test.cpp"});
 
   I.Members.emplace_back(TypeInfo("int"), "X", AccessSpecifier::AS_private);
-  I.TagType = TagTypeKind::TTK_Class;
+  I.TagType = TagTypeKind::Class;
   I.IsTypeDef = true;
   I.Bases.emplace_back(EmptySID, "F", "path/to/F", true,
                        AccessSpecifier::AS_public, true);
diff --git a/clang-tools-extra/unittests/clang-doc/HTMLGeneratorTest.cpp b/clang-tools-extra/unittests/clang-doc/HTMLGeneratorTest.cpp
index 5141259161653..9aabb1ed30e42 100644
--- a/clang-tools-extra/unittests/clang-doc/HTMLGeneratorTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/HTMLGeneratorTest.cpp
@@ -154,7 +154,7 @@ TEST(HTMLGeneratorTest, emitRecordHTML) {
   SmallString<16> PathTo;
   llvm::sys::path::native("path/to", PathTo);
   I.Members.emplace_back(TypeInfo("int"), "X", AccessSpecifier::AS_private);
-  I.TagType = TagTypeKind::TTK_Class;
+  I.TagType = TagTypeKind::Class;
   I.Parents.emplace_back(EmptySID, "F", InfoType::IT_record, "F", PathTo);
   I.VirtualParents.emplace_back(EmptySID, "G", InfoType::IT_record);
 
diff --git a/clang-tools-extra/unittests/clang-doc/MDGeneratorTest.cpp b/clang-tools-extra/unittests/clang-doc/MDGeneratorTest.cpp
index 1bbd24eebb784..d3567efd82283 100644
--- a/clang-tools-extra/unittests/clang-doc/MDGeneratorTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/MDGeneratorTest.cpp
@@ -86,7 +86,7 @@ TEST(MDGeneratorTest, emitRecordMD) {
   I.Loc.emplace_back(12, llvm::SmallString<16>{"test.cpp"});
 
   I.Members.emplace_back(TypeInfo("int"), "X", AccessSpecifier::AS_private);
-  I.TagType = TagTypeKind::TTK_Class;
+  I.TagType = TagTypeKind::Class;
   I.Parents.emplace_back(EmptySID, "F", InfoType::IT_record);
   I.VirtualParents.emplace_back(EmptySID, "G", InfoType::IT_record);
 
diff --git a/clang-tools-extra/unittests/clang-doc/MergeTest.cpp b/clang-tools-extra/unittests/clang-doc/MergeTest.cpp
index 51fddb97decf0..9aa76524194b3 100644
--- a/clang-tools-extra/unittests/clang-doc/MergeTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/MergeTest.cpp
@@ -84,7 +84,7 @@ TEST(MergeTest, mergeRecordInfos) {
   One.DefLoc = Location(10, llvm::SmallString<16>{"test.cpp"});
 
   One.Members.emplace_back(TypeInfo("int"), "X", AccessSpecifier::AS_private);
-  One.TagType = TagTypeKind::TTK_Class;
+  One.TagType = TagTypeKind::Class;
   One.Parents.emplace_back(EmptySID, "F", InfoType::IT_record);
   One.VirtualParents.emplace_back(EmptySID, "G", InfoType::IT_record);
 
@@ -105,7 +105,7 @@ TEST(MergeTest, mergeRecordInfos) {
 
   Two.Loc.emplace_back(12, llvm::SmallString<16>{"test.cpp"});
 
-  Two.TagType = TagTypeKind::TTK_Class;
+  Two.TagType = TagTypeKind::Class;
 
   Two.Children.Records.emplace_back(NonEmptySID, "SharedChildStruct",
                                     InfoType::IT_record, "path");
@@ -128,7 +128,7 @@ TEST(MergeTest, mergeRecordInfos) {
 
   Expected->Members.emplace_back(TypeInfo("int"), "X",
                                  AccessSpecifier::AS_private);
-  Expected->TagType = TagTypeKind::TTK_Class;
+  Expected->TagType = TagTypeKind::Class;
   Expected->Parents.emplace_back(EmptySID, "F", InfoType::IT_record);
   Expected->VirtualParents.emplace_back(EmptySID, "G", InfoType::IT_record);
   Expected->Bases.emplace_back(EmptySID, "F", "path/to/F", true,
diff --git a/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp b/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp
index ca370de5a516e..5df42b9f5bca0 100644
--- a/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp
@@ -167,7 +167,7 @@ typedef struct {} G;)raw",
   RecordInfo ExpectedE(EmptySID, /*Name=*/"E", /*Path=*/"GlobalNamespace");
   ExpectedE.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedE.TagType = TagTypeKind::TTK_Class;
+  ExpectedE.TagType = TagTypeKind::Class;
   ExpectedE.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   ExpectedE.Members.emplace_back(TypeInfo("int"), "value",
                                  AccessSpecifier::AS_public);
@@ -210,7 +210,7 @@ typedef struct {} G;)raw",
   RecordInfo ExpectedF(EmptySID, /*Name=*/"F", /*Path=*/"GlobalNamespace");
   ExpectedF.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedF.TagType = TagTypeKind::TTK_Struct;
+  ExpectedF.TagType = TagTypeKind::Struct;
   ExpectedF.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   CheckRecordInfo(&ExpectedF, F);
 
@@ -253,7 +253,7 @@ typedef struct {} G;)raw",
   RecordInfo ExpectedG(EmptySID, /*Name=*/"G", /*Path=*/"GlobalNamespace");
   ExpectedG.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedG.TagType = TagTypeKind::TTK_Struct;
+  ExpectedG.TagType = TagTypeKind::Struct;
   ExpectedG.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   ExpectedG.IsTypeDef = true;
   CheckRecordInfo(&ExpectedG, G);
@@ -295,7 +295,7 @@ TEST(SerializeTest, emitUndefinedRecordInfo) {
   RecordInfo ExpectedE(EmptySID, /*Name=*/"E", /*Path=*/"GlobalNamespace");
   ExpectedE.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedE.TagType = TagTypeKind::TTK_Class;
+  ExpectedE.TagType = TagTypeKind::Class;
   ExpectedE.Loc.emplace_back(0, llvm::SmallString<16>{"test.cpp"});
   CheckRecordInfo(&ExpectedE, E);
 }
@@ -308,7 +308,7 @@ TEST(SerializeTest, emitRecordMemberInfo) {
   RecordInfo ExpectedE(EmptySID, /*Name=*/"E", /*Path=*/"GlobalNamespace");
   ExpectedE.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedE.TagType = TagTypeKind::TTK_Struct;
+  ExpectedE.TagType = TagTypeKind::Struct;
   ExpectedE.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   ExpectedE.Members.emplace_back(TypeInfo("int"), "I",
                                  AccessSpecifier::AS_public);
@@ -324,7 +324,7 @@ TEST(SerializeTest, emitInternalRecordInfo) {
   ExpectedE.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
   ExpectedE.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
-  ExpectedE.TagType = TagTypeKind::TTK_Class;
+  ExpectedE.TagType = TagTypeKind::Class;
   CheckRecordInfo(&ExpectedE, E);
 
   RecordInfo *G = InfoAsRecord(Infos[2].get());
@@ -332,7 +332,7 @@ TEST(SerializeTest, emitInternalRecordInfo) {
   llvm::sys::path::native(ExpectedGPath);
   RecordInfo ExpectedG(EmptySID, /*Name=*/"G", /*Path=*/ExpectedGPath);
   ExpectedG.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
-  ExpectedG.TagType = TagTypeKind::TTK_Class;
+  ExpectedG.TagType = TagTypeKind::Class;
   ExpectedG.Namespace.emplace_back(EmptySID, "E", InfoType::IT_record);
   ExpectedG.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
@@ -391,7 +391,7 @@ class J : public I<int> {} ;)raw",
   RecordInfo ExpectedF(EmptySID, /*Name=*/"F", /*Path=*/"GlobalNamespace");
   ExpectedF.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace, "");
-  ExpectedF.TagType = TagTypeKind::TTK_Class;
+  ExpectedF.TagType = TagTypeKind::Class;
   ExpectedF.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   CheckRecordInfo(&ExpectedF, F);
 
@@ -399,7 +399,7 @@ class J : public I<int> {} ;)raw",
   RecordInfo ExpectedG(EmptySID, /*Name=*/"G", /*Path=*/"GlobalNamespace");
   ExpectedG.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedG.TagType = TagTypeKind::TTK_Class;
+  ExpectedG.TagType = TagTypeKind::Class;
   ExpectedG.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   ExpectedG.Members.emplace_back(TypeInfo("int"), "I",
                                  AccessSpecifier::AS_protected);
@@ -446,14 +446,14 @@ class J : public I<int> {} ;)raw",
   ExpectedE.Bases.back().Members.emplace_back(TypeInfo("int"), "I",
                                               AccessSpecifier::AS_private);
   ExpectedE.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
-  ExpectedE.TagType = TagTypeKind::TTK_Class;
+  ExpectedE.TagType = TagTypeKind::Class;
   CheckRecordInfo(&ExpectedE, E);
 
   RecordInfo *H = InfoAsRecord(Infos[8].get());
   RecordInfo ExpectedH(EmptySID, /*Name=*/"H", /*Path=*/"GlobalNamespace");
   ExpectedH.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedH.TagType = TagTypeKind::TTK_Class;
+  ExpectedH.TagType = TagTypeKind::Class;
   ExpectedH.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   ExpectedH.Parents.emplace_back(EmptySID, /*Name=*/"E", InfoType::IT_record,
                                  /*QualName=*/"E", /*Path=*/"GlobalNamespace");
@@ -500,7 +500,7 @@ class J : public I<int> {} ;)raw",
   RecordInfo ExpectedI(EmptySID, /*Name=*/"I", /*Path=*/"GlobalNamespace");
   ExpectedI.Namespace.emplace_back(EmptySID, "GlobalNamespace",
                                    InfoType::IT_namespace);
-  ExpectedI.TagType = TagTypeKind::TTK_Class;
+  ExpectedI.TagType = TagTypeKind::Class;
   ExpectedI.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
   CheckRecordInfo(&ExpectedI, I);
 
@@ -514,7 +514,7 @@ class J : public I<int> {} ;)raw",
                                /*Path=*/"GlobalNamespace", false,
                                AccessSpecifier::AS_public, true);
   ExpectedJ.DefLoc = Location(0, llvm::SmallString<16>{"test.cpp"});
-  ExpectedJ.TagType = TagTypeKind::TTK_Class;
+  ExpectedJ.TagType = TagTypeKind::Class;
   CheckRecordInfo(&ExpectedJ, J);
 }
 
diff --git a/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp b/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp
index 535d49169b5df..9b1d87dfa0135 100644
--- a/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp
@@ -101,7 +101,7 @@ TEST(YAMLGeneratorTest, emitRecordYAML) {
   Brief->Children.back()->Text = "Value of the thing.";
   I.Members.back().Description.push_back(std::move(TopComment));
 
-  I.TagType = TagTypeKind::TTK_Class;
+  I.TagType = TagTypeKind::Class;
   I.Bases.emplace_back(EmptySID, "F", "path/to/F", true,
                        AccessSpecifier::AS_public, true);
   I.Bases.back().Children.Functions.emplace_back();
diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index e5f78dfdc22ab..6bb3082472239 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -1197,8 +1197,9 @@ class ASTContext : public RefCountedBase<ASTContext> {
 
   /// Create a new implicit TU-level CXXRecordDecl or RecordDecl
   /// declaration.
-  RecordDecl *buildImplicitRecord(StringRef Name,
-                                  RecordDecl::TagKind TK = TTK_Struct) const;
+  RecordDecl *buildImplicitRecord(
+      StringRef Name,
+      RecordDecl::TagKind TK = RecordDecl::TagKind::Struct) const;
 
   /// Create a new implicit TU-level typedef declaration.
   TypedefDecl *buildImplicitTypedef(QualType T, StringRef Name) const;
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index d8ea8c1dfb4f2..d8495f2c34940 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -3703,13 +3703,15 @@ class TagDecl : public TypeDecl,
     return static_cast<TagKind>(TagDeclBits.TagDeclKind);
   }
 
-  void setTagKind(TagKind TK) { TagDeclBits.TagDeclKind = TK; }
+  void setTagKind(TagKind TK) {
+    TagDeclBits.TagDeclKind = llvm::to_underlying(TK);
+  }
 
-  bool isStruct() const { return getTagKind() == TTK_Struct; }
-  bool isInterface() const { return getTagKind() == TTK_Interface; }
-  bool isClass()  const { return getTagKind() == TTK_Class; }
-  bool isUnion()  const { return getTagKind() == TTK_Union; }
-  bool isEnum()   const { return getTagKind() == TTK_Enum; }
+  bool isStruct() const { return getTagKind() == TagTypeKind::Struct; }
+  bool isInterface() const { return getTagKind() == TagTypeKind::Interface; }
+  bool isClass() const { return getTagKind() == TagTypeKind::Class; }
+  bool isUnion() const { return getTagKind() == TagTypeKind::Union; }
+  bool isEnum() const { return getTagKind() == TagTypeKind::Enum; }
 
   /// Is this tag type named, either directly or via being defined in
   /// a typedef of this type?
diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index f64cd5e0ef649..42e9b8f94b4e7 100644
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -5718,21 +5718,21 @@ enum class ElaboratedTypeKeyword {
 };
 
 /// The kind of a tag type.
-enum TagTypeKind {
+enum class TagTypeKind {
   /// The "struct" keyword.
-  TTK_Struct,
+  Struct,
 
   /// The "__interface" keyword.
-  TTK_Interface,
+  Interface,
 
   /// The "union" keyword.
-  TTK_Union,
+  Union,
 
   /// The "class" keyword.
-  TTK_Class,
+  Class,
 
   /// The "enum" keyword.
-  TTK_Enum
+  Enum
 };
 
 /// A helper class for Type nodes having an ElaboratedTypeKeyword.
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 1cb81cffd37ea..da90136752210 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -6525,12 +6525,12 @@ bool ASTContext::isSameEntity(const NamedDecl *X, const NamedDecl *Y) const {
   if (const auto *TagX = dyn_cast<TagDecl>(X)) {
     const auto *TagY = cast<TagDecl>(Y);
     return (TagX->getTagKind() == TagY->getTagKind()) ||
-           ((TagX->getTagKind() == TTK_Struct ||
-             TagX->getTagKind() == TTK_Class ||
-             TagX->getTagKind() == TTK_Interface) &&
-            (TagY->getTagKind() == TTK_Struct ||
-             TagY->getTagKind() == TTK_Class ||
-             TagY->getTagKind() == TTK_Interface));
+           ((TagX->getTagKind() == TagTypeKind::Struct ||
+             TagX->getTagKind() == TagTypeKind::Class ||
+             TagX->getTagKind() == TagTypeKind::Interface) &&
+            (TagY->getTagKind() == TagTypeKind::Struct ||
+             TagY->getTagKind() == TagTypeKind::Class ||
+             TagY->getTagKind() == TagTypeKind::Interface));
   }
 
   // Functions with the same type and linkage match.
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 42ba8582c46de..ed848e5742334 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4639,8 +4639,8 @@ TagDecl::TagDecl(Kind DK, TagKind TK, const ASTContext &C, DeclContext *DC,
                  SourceLocation StartL)
     : TypeDecl(DK, DC, L, Id, StartL), DeclContext(DK), redeclarable_base(C),
       TypedefNameDeclOrQualifier((TypedefNameDecl *)nullptr) {
-  assert((DK != Enum || TK == TTK_Enum) &&
-         "EnumDecl not matched with TTK_Enum");
+  assert((DK != Enum || TK == TagTypeKind::Enum) &&
+         "EnumDecl not matched with TagTypeKind::Enum");
   setPreviousDecl(PrevDecl);
   setTagKind(TK);
   setCompleteDefinition(false);
@@ -4773,7 +4773,7 @@ void TagDecl::setTemplateParameterListsInfo(
 EnumDecl::EnumDecl(ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
                    SourceLocation IdLoc, IdentifierInfo *Id, EnumDecl *PrevDecl,
                    bool Scoped, bool ScopedUsingClassTag, bool Fixed)
-    : TagDecl(Enum, TTK_Enum, C, DC, IdLoc, Id, PrevDecl, StartLoc) {
+    : TagDecl(Enum, TagTypeKind::Enum, C, DC, IdLoc, Id, PrevDecl, StartLoc) {
   assert(Scoped || !ScopedUsingClassTag);
   IntegerType = nullptr;
   setNumPositiveBits(0);
@@ -4962,9 +4962,9 @@ RecordDecl *RecordDecl::Create(const ASTContext &C, TagKind TK, DeclContext *DC,
 }
 
 RecordDecl *RecordDecl::CreateDeserialized(const ASTContext &C, unsigned ID) {
-  RecordDecl *R =
-      new (C, ID) RecordDecl(Record, TTK_Struct, C, nullptr, SourceLocation(),
-                             SourceLocation(), nullptr, nullptr);
+  RecordDecl *R = new (C, ID)
+      RecordDecl(Record, TagTypeKind::Struct, C, nullptr, SourceLocation(),
+                 SourceLocation(), nullptr, nullptr);
   R->setMayHaveOutOfDateDef(C.getLangOpts().Modules);
   return R;
 }
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 4002c63e9f94c..c944862fcefee 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -148,8 +148,8 @@ CXXRecordDecl::CreateLambda(const ASTContext &C, DeclContext *DC,
                             TypeSourceInfo *Info, SourceLocation Loc,
                             unsigned DependencyKind, bool IsGeneric,
                             LambdaCaptureDefault CaptureDefault) {
-  auto *R = new (C, DC) CXXRecordDecl(CXXRecord, TTK_Class, C, DC, Loc, Loc,
-                                      nullptr, nullptr);
+  auto *R = new (C, DC) CXXRecordDecl(CXXRecord, TagTypeKind::Class, C, DC, Loc,
+                                      Loc, nullptr, nullptr);
   R->setBeingDefined(true);
   R->DefinitionData = new (C) struct LambdaDefinitionData(
       R, Info, DependencyKind, IsGeneric, CaptureDefault);
@@ -162,9 +162,9 @@ CXXRecordDecl::CreateLambda(const ASTContext &C, DeclContext *DC,
 
 CXXRecordDecl *
 CXXRecordDecl::CreateDeserialized(const ASTContext &C, unsigned ID) {
-  auto *R = new (C, ID) CXXRecordDecl(
-      CXXRecord, TTK_Struct, C, nullptr, SourceLocation(), SourceLocation(),
-      nullptr, nullptr);
+  auto *R = new (C, ID)
+      CXXRecordDecl(CXXRecord, TagTypeKind::Struct, C, nullptr,
+                    SourceLocation(), SourceLocation(), nullptr, nullptr);
   R->setMayHaveOutOfDateDef(false);
   return R;
 }
@@ -692,11 +692,10 @@ bool CXXRecordDecl::lambdaIsDefaultConstructibleAndAssignable() const {
 }
 
 void CXXRecordDecl::addedMember(Decl *D) {
-  if (!D->isImplicit() &&
-      !isa<FieldDecl>(D) &&
-      !isa<IndirectFieldDecl>(D) &&
-      (!isa<TagDecl>(D) || cast<TagDecl>(D)->getTagKind() == TTK_Class ||
-        cast<TagDecl>(D)->getTagKind() == TTK_Interface))
+  if (!D->isImplicit() && !isa<FieldDecl>(D) && !isa<IndirectFieldDecl>(D) &&
+      (!isa<TagDecl>(D) ||
+       cast<TagDecl>(D)->getTagKind() == TagTypeKind::Class ||
+       cast<TagDecl>(D)->getTagKind() == TagTypeKind::Interface))
     data().HasOnlyCMembers = false;
 
   // Ignore friends and invalid declarations.
@@ -1510,7 +1509,8 @@ void CXXRecordDecl::setTrivialForCallFlags(CXXMethodDecl *D) {
 }
 
 bool CXXRecordDecl::isCLike() const {
-  if (getTagKind() == TTK_Class || getTagKind() == TTK_Interface ||
+  if (getTagKind() == TagTypeKind::Class ||
+      getTagKind() == TagTypeKind::Interface ||
       !TemplateOrInstantiation.isNull())
     return false;
   if (!hasDefinition())
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index be385ca115254..7d7556e670f95 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -920,7 +920,7 @@ ClassTemplateSpecializationDecl(ASTContext &Context, Kind DK, TagKind TK,
 
 ClassTemplateSpecializationDecl::ClassTemplateSpecializationDecl(ASTContext &C,
                                                                  Kind DK)
-    : CXXRecordDecl(DK, TTK_Struct, C, nullptr, SourceLocation(),
+    : CXXRecordDecl(DK, TagTypeKind::Struct, C, nullptr, SourceLocation(),
                     SourceLocation(), nullptr, nullptr),
       SpecializationKind(TSK_Undeclared) {}
 
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index b7cfcbc9dfa46..50ab6ea59be9d 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -1312,9 +1312,9 @@ void MicrosoftCXXNameMangler::mangleNestedName(GlobalDecl GD) {
       if (PointersAre64Bit)
         Out << 'E';
       Out << 'A';
-      mangleArtificialTagType(TTK_Struct,
-                             Discriminate("__block_literal", Discriminator,
-                                          ParameterDiscriminator));
+      mangleArtificialTagType(TagTypeKind::Struct,
+                              Discriminate("__block_literal", Discriminator,
+                                           ParameterDiscriminator));
       Out << "@Z";
 
       // If the effective context was a Record, we have fully mangled the
@@ -1974,9 +1974,9 @@ void MicrosoftCXXNameMangler::mangleObjCProtocol(const ObjCProtocolDecl *PD) {
 
   Stream << "?$";
   Extra.mangleSourceName("Protocol");
-  Extra.mangleArtificialTagType(TTK_Struct, PD->getName());
+  Extra.mangleArtificialTagType(TagTypeKind::Struct, PD->getName());
 
-  mangleArtificialTagType(TTK_Struct, TemplateMangling, {"__ObjC"});
+  mangleArtificialTagType(TagTypeKind::Struct, TemplateMangling, {"__ObjC"});
 }
 
 void MicrosoftCXXNameMangler::mangleObjCLifetime(const QualType Type,
@@ -2005,7 +2005,7 @@ void MicrosoftCXXNameMangler::mangleObjCLifetime(const QualType Type,
   Extra.manglePointerExtQualifiers(Quals, Type);
   Extra.mangleType(Type, Range);
 
-  mangleArtificialTagType(TTK_Struct, TemplateMangling, {"__ObjC"});
+  mangleArtificialTagType(TagTypeKind::Struct, TemplateMangling, {"__ObjC"});
 }
 
 void MicrosoftCXXNameMangler::mangleObjCKindOfType(const ObjCObjectType *T,
@@ -2022,7 +2022,7 @@ void MicrosoftCXXNameMangler::mangleObjCKindOfType(const ObjCObjectType *T,
                        ->castAs<ObjCObjectType>(),
                    Quals, Range);
 
-  mangleArtificialTagType(TTK_Struct, TemplateMangling, {"__ObjC"});
+  mangleArtificialTagType(TagTypeKind::Struct, TemplateMangling, {"__ObjC"});
 }
 
 void MicrosoftCXXNameMangler::mangleQualifiers(Qualifiers Quals,
@@ -2223,7 +2223,8 @@ void MicrosoftCXXNameMangler::manglePassObjectSizeArg(
   if (Found == FunArgBackReferences.end()) {
     std::string Name =
         Dynamic ? "__pass_dynamic_object_size" : "__pass_object_size";
-    mangleArtificialTagType(TTK_Enum, Name + llvm::utostr(Type), {"__clang"});
+    mangleArtificialTagType(TagTypeKind::Enum, Name + llvm::utostr(Type),
+                            {"__clang"});
 
     if (FunArgBackReferences.size() < 10) {
       size_t Size = FunArgBackReferences.size();
@@ -2304,7 +2305,7 @@ void MicrosoftCXXNameMangler::mangleAddressSpaceType(QualType T,
 
   Extra.mangleType(T, Range, QMM_Escape);
   mangleQualifiers(Qualifiers(), false);
-  mangleArtificialTagType(TTK_Struct, ASMangling, {"__clang"});
+  mangleArtificialTagType(TagTypeKind::Struct, ASMangling, {"__clang"});
 }
 
 void MicrosoftCXXNameMangler::mangleType(QualType T, SourceRange Range,
@@ -2486,13 +2487,13 @@ void MicrosoftCXXNameMangler::mangleType(const BuiltinType *T, Qualifiers,
     llvm_unreachable("placeholder types shouldn't get to name mangling");
 
   case BuiltinType::ObjCId:
-    mangleArtificialTagType(TTK_Struct, "objc_object");
+    mangleArtificialTagType(TagTypeKind::Struct, "objc_object");
     break;
   case BuiltinType::ObjCClass:
-    mangleArtificialTagType(TTK_Struct, "objc_class");
+    mangleArtificialTagType(TagTypeKind::Struct, "objc_class");
     break;
   case BuiltinType::ObjCSel:
-    mangleArtificialTagType(TTK_Struct, "objc_selector");
+    mangleArtificialTagType(TagTypeKind::Struct, "objc_selector");
     break;
 
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
@@ -2502,27 +2503,27 @@ void MicrosoftCXXNameMangler::mangleType(const BuiltinType *T, Qualifiers,
 #include "clang/Basic/OpenCLImageTypes.def"
   case BuiltinType::OCLSampler:
     Out << "PA";
-    mangleArtificialTagType(TTK_Struct, "ocl_sampler");
+    mangleArtificialTagType(TagTypeKind::Struct, "ocl_sampler");
     break;
   case BuiltinType::OCLEvent:
     Out << "PA";
-    mangleArtificialTagType(TTK_Struct, "ocl_event");
+    mangleArtificialTagType(TagTypeKind::Struct, "ocl_event");
     break;
   case BuiltinType::OCLClkEvent:
     Out << "PA";
-    mangleArtificialTagType(TTK_Struct, "ocl_clkevent");
+    mangleArtificialTagType(TagTypeKind::Struct, "ocl_clkevent");
     break;
   case BuiltinType::OCLQueue:
     Out << "PA";
-    mangleArtificialTagType(TTK_Struct, "ocl_queue");
+    mangleArtificialTagType(TagTypeKind::Struct, "ocl_queue");
     break;
   case BuiltinType::OCLReserveID:
     Out << "PA";
-    mangleArtificialTagType(TTK_Struct, "ocl_reserveid");
+    mangleArtificialTagType(TagTypeKind::Struct, "ocl_reserveid");
     break;
-#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
-  case BuiltinType::Id: \
-    mangleArtificialTagType(TTK_Struct, "ocl_" #ExtType); \
+#define EXT_OPAQUE_TYPE(ExtType, Id, Ext)                                      \
+  case BuiltinType::Id:                                                        \
+    mangleArtificialTagType(TagTypeKind::Struct, "ocl_" #ExtType);             \
     break;
 #include "clang/Basic/OpenCLExtensionTypes.def"
 
@@ -2531,12 +2532,12 @@ void MicrosoftCXXNameMangler::mangleType(const BuiltinType *T, Qualifiers,
     break;
 
   case BuiltinType::Float16:
-    mangleArtificialTagType(TTK_Struct, "_Float16", {"__clang"});
+    mangleArtificialTagType(TagTypeKind::Struct, "_Float16", {"__clang"});
     break;
 
   case BuiltinType::Half:
     if (!getASTContext().getLangOpts().HLSL)
-      mangleArtificialTagType(TTK_Struct, "_Half", {"__clang"});
+      mangleArtificialTagType(TagTypeKind::Struct, "_Half", {"__clang"});
     else if (getASTContext().getLangOpts().NativeHalfType)
       Out << "$f16@";
     else
@@ -2544,13 +2545,13 @@ void MicrosoftCXXNameMangler::mangleType(const BuiltinType *T, Qualifiers,
     break;
 
   case BuiltinType::BFloat16:
-    mangleArtificialTagType(TTK_Struct, "__bf16", {"__clang"});
+    mangleArtificialTagType(TagTypeKind::Struct, "__bf16", {"__clang"});
     break;
 
 #define WASM_REF_TYPE(InternalName, MangledName, Id, SingletonId, AS)          \
   case BuiltinType::Id:                                                        \
-    mangleArtificialTagType(TTK_Struct, MangledName);                          \
-    mangleArtificialTagType(TTK_Struct, MangledName, {"__clang"});             \
+    mangleArtificialTagType(TagTypeKind::Struct, MangledName);                 \
+    mangleArtificialTagType(TagTypeKind::Struct, MangledName, {"__clang"});    \
     break;
 
 #include "clang/Basic/WebAssemblyReferenceTypes.def"
@@ -2917,19 +2918,19 @@ void MicrosoftCXXNameMangler::mangleType(const UnresolvedUsingType *T,
 // <enum-type>   ::= W4 <name>
 void MicrosoftCXXNameMangler::mangleTagTypeKind(TagTypeKind TTK) {
   switch (TTK) {
-    case TTK_Union:
-      Out << 'T';
-      break;
-    case TTK_Struct:
-    case TTK_Interface:
-      Out << 'U';
-      break;
-    case TTK_Class:
-      Out << 'V';
-      break;
-    case TTK_Enum:
-      Out << "W4";
-      break;
+  case TagTypeKind::Union:
+    Out << 'T';
+    break;
+  case TagTypeKind::Struct:
+  case TagTypeKind::Interface:
+    Out << 'U';
+    break;
+  case TagTypeKind::Class:
+    Out << 'V';
+    break;
+  case TagTypeKind::Enum:
+    Out << "W4";
+    break;
   }
 }
 void MicrosoftCXXNameMangler::mangleType(const EnumType *T, Qualifiers,
@@ -3139,11 +3140,11 @@ void MicrosoftCXXNameMangler::mangleType(const ComplexType *T, Qualifiers,
   Extra.mangleSourceName("_Complex");
   Extra.mangleType(ElementType, Range, QMM_Escape);
 
-  mangleArtificialTagType(TTK_Struct, TemplateMangling, {"__clang"});
+  mangleArtificialTagType(TagTypeKind::Struct, TemplateMangling, {"__clang"});
 }
 
 // Returns true for types that mangleArtificialTagType() gets called for with
-// TTK_Union, TTK_Struct, TTK_Class and where compatibility with MSVC's
+// TagTypeKind Union, Struct, Class and where compatibility with MSVC's
 // mangling matters.
 // (It doesn't matter for Objective-C types and the like that cl.exe doesn't
 // support.)
@@ -3176,14 +3177,17 @@ void MicrosoftCXXNameMangler::mangleType(const VectorType *T, Qualifiers Quals,
   if (!isa<ExtVectorType>(T)) {
     if (getASTContext().getTargetInfo().getTriple().isX86() && ET) {
       if (Width == 64 && ET->getKind() == BuiltinType::LongLong) {
-        mangleArtificialTagType(TTK_Union, "__m64");
+        mangleArtificialTagType(TagTypeKind::Union, "__m64");
       } else if (Width >= 128) {
         if (ET->getKind() == BuiltinType::Float)
-          mangleArtificialTagType(TTK_Union, "__m" + llvm::utostr(Width));
+          mangleArtificialTagType(TagTypeKind::Union,
+                                  "__m" + llvm::utostr(Width));
         else if (ET->getKind() == BuiltinType::LongLong)
-          mangleArtificialTagType(TTK_Union, "__m" + llvm::utostr(Width) + 'i');
+          mangleArtificialTagType(TagTypeKind::Union,
+                                  "__m" + llvm::utostr(Width) + 'i');
         else if (ET->getKind() == BuiltinType::Double)
-          mangleArtificialTagType(TTK_Struct, "__m" + llvm::utostr(Width) + 'd');
+          mangleArtificialTagType(TagTypeKind::Struct,
+                                  "__m" + llvm::utostr(Width) + 'd');
       }
     }
   }
@@ -3203,7 +3207,7 @@ void MicrosoftCXXNameMangler::mangleType(const VectorType *T, Qualifiers Quals,
                      Range, QMM_Escape);
     Extra.mangleIntegerLiteral(llvm::APSInt::getUnsigned(T->getNumElements()));
 
-    mangleArtificialTagType(TTK_Union, TemplateMangling, {"__clang"});
+    mangleArtificialTagType(TagTypeKind::Union, TemplateMangling, {"__clang"});
   }
 }
 
@@ -3259,7 +3263,7 @@ void MicrosoftCXXNameMangler::mangleType(const DependentAddressSpaceType *T,
 void MicrosoftCXXNameMangler::mangleType(const ObjCInterfaceType *T, Qualifiers,
                                          SourceRange) {
   // ObjC interfaces have structs underlying them.
-  mangleTagTypeKind(TTK_Struct);
+  mangleTagTypeKind(TagTypeKind::Struct);
   mangleName(T->getDecl());
 }
 
@@ -3279,7 +3283,7 @@ void MicrosoftCXXNameMangler::mangleType(const ObjCObjectType *T,
   TemplateArgBackReferences.swap(OuterTemplateArgsContext);
   NameBackReferences.swap(OuterTemplateContext);
 
-  mangleTagTypeKind(TTK_Struct);
+  mangleTagTypeKind(TagTypeKind::Struct);
 
   Out << "?$";
   if (T->isObjCId())
@@ -3427,7 +3431,7 @@ void MicrosoftCXXNameMangler::mangleType(const AtomicType *T, Qualifiers,
   Extra.mangleSourceName("_Atomic");
   Extra.mangleType(ValueType, Range, QMM_Escape);
 
-  mangleArtificialTagType(TTK_Struct, TemplateMangling, {"__clang"});
+  mangleArtificialTagType(TagTypeKind::Struct, TemplateMangling, {"__clang"});
 }
 
 void MicrosoftCXXNameMangler::mangleType(const PipeType *T, Qualifiers,
@@ -3442,7 +3446,7 @@ void MicrosoftCXXNameMangler::mangleType(const PipeType *T, Qualifiers,
   Extra.mangleType(ElementType, Range, QMM_Escape);
   Extra.mangleIntegerLiteral(llvm::APSInt::get(T->isReadOnly()));
 
-  mangleArtificialTagType(TTK_Struct, TemplateMangling, {"__clang"});
+  mangleArtificialTagType(TagTypeKind::Struct, TemplateMangling, {"__clang"});
 }
 
 void MicrosoftMangleContextImpl::mangleCXXName(GlobalDecl GD,
@@ -3482,7 +3486,7 @@ void MicrosoftCXXNameMangler::mangleType(const BitIntType *T, Qualifiers,
     Extra.mangleSourceName("_BitInt");
   Extra.mangleIntegerLiteral(llvm::APSInt::getUnsigned(T->getNumBits()));
 
-  mangleArtificialTagType(TTK_Struct, TemplateMangling, {"__clang"});
+  mangleArtificialTagType(TagTypeKind::Struct, TemplateMangling, {"__clang"});
 }
 
 void MicrosoftCXXNameMangler::mangleType(const DependentBitIntType *T,
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index 5d4f930fca50e..a51c8b938f411 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -2267,9 +2267,12 @@ ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
 /// \returns diagnostic %select index.
 static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag) {
   switch (Tag) {
-  case TTK_Struct: return 0;
-  case TTK_Interface: return 1;
-  case TTK_Class: return 2;
+  case TagTypeKind::Struct:
+    return 0;
+  case TagTypeKind::Interface:
+    return 1;
+  case TagTypeKind::Class:
+    return 2;
   default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
   }
 }
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index d1cbfbd150ba5..4dd4e926c8104 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -3035,11 +3035,16 @@ TypeWithKeyword::getKeywordForTypeSpec(unsigned TypeSpec) {
 TagTypeKind
 TypeWithKeyword::getTagTypeKindForTypeSpec(unsigned TypeSpec) {
   switch(TypeSpec) {
-  case TST_class: return TTK_Class;
-  case TST_struct: return TTK_Struct;
-  case TST_interface: return TTK_Interface;
-  case TST_union: return TTK_Union;
-  case TST_enum: return TTK_Enum;
+  case TST_class:
+    return TagTypeKind::Class;
+  case TST_struct:
+    return TagTypeKind::Struct;
+  case TST_interface:
+    return TagTypeKind::Interface;
+  case TST_union:
+    return TagTypeKind::Union;
+  case TST_enum:
+    return TagTypeKind::Enum;
   }
 
   llvm_unreachable("Type specifier is not a tag type kind.");
@@ -3048,15 +3053,15 @@ TypeWithKeyword::getTagTypeKindForTypeSpec(unsigned TypeSpec) {
 ElaboratedTypeKeyword
 TypeWithKeyword::getKeywordForTagTypeKind(TagTypeKind Kind) {
   switch (Kind) {
-  case TTK_Class:
+  case TagTypeKind::Class:
     return ElaboratedTypeKeyword::Class;
-  case TTK_Struct:
+  case TagTypeKind::Struct:
     return ElaboratedTypeKeyword::Struct;
-  case TTK_Interface:
+  case TagTypeKind::Interface:
     return ElaboratedTypeKeyword::Interface;
-  case TTK_Union:
+  case TagTypeKind::Union:
     return ElaboratedTypeKeyword::Union;
-  case TTK_Enum:
+  case TagTypeKind::Enum:
     return ElaboratedTypeKeyword::Enum;
   }
   llvm_unreachable("Unknown tag type kind.");
@@ -3066,15 +3071,15 @@ TagTypeKind
 TypeWithKeyword::getTagTypeKindForKeyword(ElaboratedTypeKeyword Keyword) {
   switch (Keyword) {
   case ElaboratedTypeKeyword::Class:
-    return TTK_Class;
+    return TagTypeKind::Class;
   case ElaboratedTypeKeyword::Struct:
-    return TTK_Struct;
+    return TagTypeKind::Struct;
   case ElaboratedTypeKeyword::Interface:
-    return TTK_Interface;
+    return TagTypeKind::Interface;
   case ElaboratedTypeKeyword::Union:
-    return TTK_Union;
+    return TagTypeKind::Union;
   case ElaboratedTypeKeyword::Enum:
-    return TTK_Enum;
+    return TagTypeKind::Enum;
   case ElaboratedTypeKeyword::None: // Fall through.
   case ElaboratedTypeKeyword::Typename:
     llvm_unreachable("Elaborated type keyword is not a tag type kind.");
diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
index b7aa3a4cb6373..6dd7ca64e5221 100644
--- a/clang/lib/CodeGen/CGObjCMac.cpp
+++ b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -5757,10 +5757,9 @@ ObjCCommonTypesHelper::ObjCCommonTypesHelper(CodeGen::CodeGenModule &cgm)
   //   id self;
   //   Class cls;
   // }
-  RecordDecl *RD = RecordDecl::Create(Ctx, TTK_Struct,
-                                      Ctx.getTranslationUnitDecl(),
-                                      SourceLocation(), SourceLocation(),
-                                      &Ctx.Idents.get("_objc_super"));
+  RecordDecl *RD = RecordDecl::Create(
+      Ctx, TagTypeKind::Struct, Ctx.getTranslationUnitDecl(), SourceLocation(),
+      SourceLocation(), &Ctx.Idents.get("_objc_super"));
   RD->addDecl(FieldDecl::Create(Ctx, RD, SourceLocation(), SourceLocation(),
                                 nullptr, Ctx.getObjCIdType(), nullptr, nullptr,
                                 false, ICIS_NoInit));
@@ -6110,10 +6109,9 @@ ObjCNonFragileABITypesHelper::ObjCNonFragileABITypesHelper(CodeGen::CodeGenModul
   // };
 
   // First the clang type for struct _message_ref_t
-  RecordDecl *RD = RecordDecl::Create(Ctx, TTK_Struct,
-                                      Ctx.getTranslationUnitDecl(),
-                                      SourceLocation(), SourceLocation(),
-                                      &Ctx.Idents.get("_message_ref_t"));
+  RecordDecl *RD = RecordDecl::Create(
+      Ctx, TagTypeKind::Struct, Ctx.getTranslationUnitDecl(), SourceLocation(),
+      SourceLocation(), &Ctx.Idents.get("_message_ref_t"));
   RD->addDecl(FieldDecl::Create(Ctx, RD, SourceLocation(), SourceLocation(),
                                 nullptr, Ctx.VoidPtrTy, nullptr, nullptr, false,
                                 ICIS_NoInit));
diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index 34c9c02884ec5..632a447241849 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -3041,7 +3041,7 @@ createKmpTaskTRecordDecl(CodeGenModule &CGM, OpenMPDirectiveKind Kind,
   //         kmp_int32           liter;
   //         void *              reductions;
   //       };
-  RecordDecl *UD = C.buildImplicitRecord("kmp_cmplrdata_t", TTK_Union);
+  RecordDecl *UD = C.buildImplicitRecord("kmp_cmplrdata_t", TagTypeKind::Union);
   UD->startDefinition();
   addFieldToRecordDecl(C, UD, KmpInt32Ty);
   addFieldToRecordDecl(C, UD, KmpRoutineEntryPointerQTy);
diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp b/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp
index 009b3f0a85a37..370613e75420e 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp
@@ -806,7 +806,7 @@ void CGOpenMPRuntimeGPU::emitKernelDeinit(CodeGenFunction &CGF,
   // This is temporary until we remove the fixed sized buffer.
   ASTContext &C = CGM.getContext();
   RecordDecl *StaticRD = C.buildImplicitRecord(
-      "_openmp_teams_reduction_type_$_", RecordDecl::TagKind::TTK_Union);
+      "_openmp_teams_reduction_type_$_", RecordDecl::TagKind::Union);
   StaticRD->startDefinition();
   for (const RecordDecl *TeamReductionRec : TeamsReductions) {
     QualType RecTy = C.getRecordType(TeamReductionRec);
diff --git a/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp b/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
index c645355d5aecd..c458700837f4e 100644
--- a/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
+++ b/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
@@ -864,9 +864,9 @@ RewriteModernObjC::getIvarAccessString(ObjCIvarDecl *D) {
         CDecl = CatDecl->getClassInterface();
       std::string RecName = std::string(CDecl->getName());
       RecName += "_IMPL";
-      RecordDecl *RD =
-          RecordDecl::Create(*Context, TTK_Struct, TUDecl, SourceLocation(),
-                             SourceLocation(), &Context->Idents.get(RecName));
+      RecordDecl *RD = RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
+                                          SourceLocation(), SourceLocation(),
+                                          &Context->Idents.get(RecName));
       QualType PtrStructIMPL = Context->getPointerType(Context->getTagDeclType(RD));
       unsigned UnsignedIntSize =
       static_cast<unsigned>(Context->getTypeSize(Context->UnsignedIntTy));
@@ -2978,9 +2978,9 @@ Stmt *RewriteModernObjC::RewriteObjCDictionaryLiteralExpr(ObjCDictionaryLiteral
 // };
 QualType RewriteModernObjC::getSuperStructType() {
   if (!SuperStructDecl) {
-    SuperStructDecl = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
-                                         SourceLocation(), SourceLocation(),
-                                         &Context->Idents.get("__rw_objc_super"));
+    SuperStructDecl = RecordDecl::Create(
+        *Context, TagTypeKind::Struct, TUDecl, SourceLocation(),
+        SourceLocation(), &Context->Idents.get("__rw_objc_super"));
     QualType FieldTypes[2];
 
     // struct objc_object *object;
@@ -3006,9 +3006,9 @@ QualType RewriteModernObjC::getSuperStructType() {
 
 QualType RewriteModernObjC::getConstantStringStructType() {
   if (!ConstantStringDecl) {
-    ConstantStringDecl = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
-                                            SourceLocation(), SourceLocation(),
-                         &Context->Idents.get("__NSConstantStringImpl"));
+    ConstantStringDecl = RecordDecl::Create(
+        *Context, TagTypeKind::Struct, TUDecl, SourceLocation(),
+        SourceLocation(), &Context->Idents.get("__NSConstantStringImpl"));
     QualType FieldTypes[4];
 
     // struct objc_object *receiver;
@@ -3782,10 +3782,9 @@ QualType RewriteModernObjC::SynthesizeBitfieldGroupStructType(
                               SmallVectorImpl<ObjCIvarDecl *> &IVars) {
   std::string StructTagName;
   ObjCIvarBitfieldGroupType(IV, StructTagName);
-  RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct,
-                                      Context->getTranslationUnitDecl(),
-                                      SourceLocation(), SourceLocation(),
-                                      &Context->Idents.get(StructTagName));
+  RecordDecl *RD = RecordDecl::Create(
+      *Context, TagTypeKind::Struct, Context->getTranslationUnitDecl(),
+      SourceLocation(), SourceLocation(), &Context->Idents.get(StructTagName));
   for (unsigned i=0, e = IVars.size(); i < e; i++) {
     ObjCIvarDecl *Ivar = IVars[i];
     RD->addDecl(FieldDecl::Create(*Context, RD, SourceLocation(), SourceLocation(),
@@ -4588,7 +4587,7 @@ Stmt *RewriteModernObjC::SynthesizeBlockCall(CallExpr *Exp, const Expr *BlockExp
   const FunctionProtoType *FTP = dyn_cast<FunctionProtoType>(FT);
   // FTP will be null for closures that don't take arguments.
 
-  RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
+  RecordDecl *RD = RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
                                       SourceLocation(), SourceLocation(),
                                       &Context->Idents.get("__block_impl"));
   QualType PtrBlock = Context->getPointerType(Context->getTagDeclType(RD));
@@ -5347,9 +5346,9 @@ Stmt *RewriteModernObjC::SynthBlockInitExpr(BlockExpr *Exp,
       RewriteByRefString(RecName, Name, ND, true);
       IdentifierInfo *II = &Context->Idents.get(RecName.c_str()
                                                 + sizeof("struct"));
-      RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
-                                          SourceLocation(), SourceLocation(),
-                                          II);
+      RecordDecl *RD =
+          RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
+                             SourceLocation(), SourceLocation(), II);
       assert(RD && "SynthBlockInitExpr(): Can't find RecordDecl");
       QualType castT = Context->getPointerType(Context->getTagDeclType(RD));
 
@@ -7508,8 +7507,8 @@ Stmt *RewriteModernObjC::RewriteObjCIvarRefExpr(ObjCIvarRefExpr *IV) {
           std::string RecName = std::string(CDecl->getName());
           RecName += "_IMPL";
           RecordDecl *RD = RecordDecl::Create(
-              *Context, TTK_Struct, TUDecl, SourceLocation(), SourceLocation(),
-              &Context->Idents.get(RecName));
+              *Context, TagTypeKind::Struct, TUDecl, SourceLocation(),
+              SourceLocation(), &Context->Idents.get(RecName));
           QualType PtrStructIMPL = Context->getPointerType(Context->getTagDeclType(RD));
           unsigned UnsignedIntSize =
             static_cast<unsigned>(Context->getTypeSize(Context->UnsignedIntTy));
diff --git a/clang/lib/Frontend/Rewrite/RewriteObjC.cpp b/clang/lib/Frontend/Rewrite/RewriteObjC.cpp
index 89ffb8908d37b..71d0e95f9bf37 100644
--- a/clang/lib/Frontend/Rewrite/RewriteObjC.cpp
+++ b/clang/lib/Frontend/Rewrite/RewriteObjC.cpp
@@ -2357,7 +2357,7 @@ void RewriteObjC::SynthMsgSendFunctionDecl() {
 void RewriteObjC::SynthMsgSendSuperFunctionDecl() {
   IdentifierInfo *msgSendIdent = &Context->Idents.get("objc_msgSendSuper");
   SmallVector<QualType, 16> ArgTys;
-  RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
+  RecordDecl *RD = RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
                                       SourceLocation(), SourceLocation(),
                                       &Context->Idents.get("objc_super"));
   QualType argT = Context->getPointerType(Context->getTagDeclType(RD));
@@ -2400,7 +2400,7 @@ void RewriteObjC::SynthMsgSendSuperStretFunctionDecl() {
   IdentifierInfo *msgSendIdent =
     &Context->Idents.get("objc_msgSendSuper_stret");
   SmallVector<QualType, 16> ArgTys;
-  RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
+  RecordDecl *RD = RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
                                       SourceLocation(), SourceLocation(),
                                       &Context->Idents.get("objc_super"));
   QualType argT = Context->getPointerType(Context->getTagDeclType(RD));
@@ -2531,7 +2531,7 @@ Stmt *RewriteObjC::RewriteObjCStringLiteral(ObjCStringLiteral *Exp) {
 // struct objc_super { struct objc_object *receiver; struct objc_class *super; };
 QualType RewriteObjC::getSuperStructType() {
   if (!SuperStructDecl) {
-    SuperStructDecl = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
+    SuperStructDecl = RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
                                          SourceLocation(), SourceLocation(),
                                          &Context->Idents.get("objc_super"));
     QualType FieldTypes[2];
@@ -2559,9 +2559,9 @@ QualType RewriteObjC::getSuperStructType() {
 
 QualType RewriteObjC::getConstantStringStructType() {
   if (!ConstantStringDecl) {
-    ConstantStringDecl = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
-                                            SourceLocation(), SourceLocation(),
-                         &Context->Idents.get("__NSConstantStringImpl"));
+    ConstantStringDecl = RecordDecl::Create(
+        *Context, TagTypeKind::Struct, TUDecl, SourceLocation(),
+        SourceLocation(), &Context->Idents.get("__NSConstantStringImpl"));
     QualType FieldTypes[4];
 
     // struct objc_object *receiver;
@@ -3755,7 +3755,7 @@ Stmt *RewriteObjC::SynthesizeBlockCall(CallExpr *Exp, const Expr *BlockExp) {
   const FunctionProtoType *FTP = dyn_cast<FunctionProtoType>(FT);
   // FTP will be null for closures that don't take arguments.
 
-  RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
+  RecordDecl *RD = RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
                                       SourceLocation(), SourceLocation(),
                                       &Context->Idents.get("__block_impl"));
   QualType PtrBlock = Context->getPointerType(Context->getTagDeclType(RD));
@@ -4483,9 +4483,9 @@ Stmt *RewriteObjC::SynthBlockInitExpr(BlockExpr *Exp,
       RewriteByRefString(RecName, Name, ND, true);
       IdentifierInfo *II = &Context->Idents.get(RecName.c_str()
                                                 + sizeof("struct"));
-      RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
-                                          SourceLocation(), SourceLocation(),
-                                          II);
+      RecordDecl *RD =
+          RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
+                             SourceLocation(), SourceLocation(), II);
       assert(RD && "SynthBlockInitExpr(): Can't find RecordDecl");
       QualType castT = Context->getPointerType(Context->getTagDeclType(RD));
 
@@ -5821,9 +5821,9 @@ Stmt *RewriteObjCFragileABI::RewriteObjCIvarRefExpr(ObjCIvarRefExpr *IV) {
           std::string(clsDeclared->getIdentifier()->getName());
       RecName += "_IMPL";
       IdentifierInfo *II = &Context->Idents.get(RecName);
-      RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
-                                          SourceLocation(), SourceLocation(),
-                                          II);
+      RecordDecl *RD =
+          RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
+                             SourceLocation(), SourceLocation(), II);
       assert(RD && "RewriteObjCIvarRefExpr(): Can't find RecordDecl");
       QualType castT = Context->getPointerType(Context->getTagDeclType(RD));
       CastExpr *castExpr = NoTypeInfoCStyleCastExpr(Context, castT,
@@ -5862,9 +5862,9 @@ Stmt *RewriteObjCFragileABI::RewriteObjCIvarRefExpr(ObjCIvarRefExpr *IV) {
           std::string(clsDeclared->getIdentifier()->getName());
       RecName += "_IMPL";
       IdentifierInfo *II = &Context->Idents.get(RecName);
-      RecordDecl *RD = RecordDecl::Create(*Context, TTK_Struct, TUDecl,
-                                          SourceLocation(), SourceLocation(),
-                                          II);
+      RecordDecl *RD =
+          RecordDecl::Create(*Context, TagTypeKind::Struct, TUDecl,
+                             SourceLocation(), SourceLocation(), II);
       assert(RD && "RewriteObjCIvarRefExpr(): Can't find RecordDecl");
       QualType castT = Context->getPointerType(Context->getTagDeclType(RD));
       CastExpr *castExpr = NoTypeInfoCStyleCastExpr(Context, castT,
diff --git a/clang/lib/Index/IndexSymbol.cpp b/clang/lib/Index/IndexSymbol.cpp
index 10384660d2cb6..c67810ad126b6 100644
--- a/clang/lib/Index/IndexSymbol.cpp
+++ b/clang/lib/Index/IndexSymbol.cpp
@@ -107,19 +107,19 @@ SymbolInfo index::getSymbolInfo(const Decl *D) {
 
   if (const TagDecl *TD = dyn_cast<TagDecl>(D)) {
     switch (TD->getTagKind()) {
-    case TTK_Struct:
+    case TagTypeKind::Struct:
       Info.Kind = SymbolKind::Struct; break;
-    case TTK_Union:
+    case TagTypeKind::Union:
       Info.Kind = SymbolKind::Union; break;
-    case TTK_Class:
+    case TagTypeKind::Class:
       Info.Kind = SymbolKind::Class;
       Info.Lang = SymbolLanguage::CXX;
       break;
-    case TTK_Interface:
+    case TagTypeKind::Interface:
       Info.Kind = SymbolKind::Protocol;
       Info.Lang = SymbolLanguage::CXX;
       break;
-    case TTK_Enum:
+    case TagTypeKind::Enum:
       Info.Kind = SymbolKind::Enum; break;
     }
 
diff --git a/clang/lib/Index/USRGeneration.cpp b/clang/lib/Index/USRGeneration.cpp
index 0eee6fe6d8207..fb936d9fbf8ab 100644
--- a/clang/lib/Index/USRGeneration.cpp
+++ b/clang/lib/Index/USRGeneration.cpp
@@ -519,11 +519,16 @@ void USRGenerator::VisitTagDecl(const TagDecl *D) {
       AlreadyStarted = true;
 
       switch (D->getTagKind()) {
-      case TTK_Interface:
-      case TTK_Class:
-      case TTK_Struct: Out << "@ST"; break;
-      case TTK_Union:  Out << "@UT"; break;
-      case TTK_Enum: llvm_unreachable("enum template");
+      case TagTypeKind::Interface:
+      case TagTypeKind::Class:
+      case TagTypeKind::Struct:
+        Out << "@ST";
+        break;
+      case TagTypeKind::Union:
+        Out << "@UT";
+        break;
+      case TagTypeKind::Enum:
+        llvm_unreachable("enum template");
       }
       VisitTemplateParameterList(ClassTmpl->getTemplateParameters());
     } else if (const ClassTemplatePartialSpecializationDecl *PartialSpec
@@ -531,11 +536,16 @@ void USRGenerator::VisitTagDecl(const TagDecl *D) {
       AlreadyStarted = true;
 
       switch (D->getTagKind()) {
-      case TTK_Interface:
-      case TTK_Class:
-      case TTK_Struct: Out << "@SP"; break;
-      case TTK_Union:  Out << "@UP"; break;
-      case TTK_Enum: llvm_unreachable("enum partial specialization");
+      case TagTypeKind::Interface:
+      case TagTypeKind::Class:
+      case TagTypeKind::Struct:
+        Out << "@SP";
+        break;
+      case TagTypeKind::Union:
+        Out << "@UP";
+        break;
+      case TagTypeKind::Enum:
+        llvm_unreachable("enum partial specialization");
       }
       VisitTemplateParameterList(PartialSpec->getTemplateParameters());
     }
@@ -543,11 +553,17 @@ void USRGenerator::VisitTagDecl(const TagDecl *D) {
 
   if (!AlreadyStarted) {
     switch (D->getTagKind()) {
-      case TTK_Interface:
-      case TTK_Class:
-      case TTK_Struct: Out << "@S"; break;
-      case TTK_Union:  Out << "@U"; break;
-      case TTK_Enum:   Out << "@E"; break;
+    case TagTypeKind::Interface:
+    case TagTypeKind::Class:
+    case TagTypeKind::Struct:
+      Out << "@S";
+      break;
+    case TagTypeKind::Union:
+      Out << "@U";
+      break;
+    case TagTypeKind::Enum:
+      Out << "@E";
+      break;
     }
   }
 
diff --git a/clang/lib/Sema/HLSLExternalSemaSource.cpp b/clang/lib/Sema/HLSLExternalSemaSource.cpp
index 0be76d4b36e04..8de144486c91d 100644
--- a/clang/lib/Sema/HLSLExternalSemaSource.cpp
+++ b/clang/lib/Sema/HLSLExternalSemaSource.cpp
@@ -62,9 +62,9 @@ struct BuiltinTypeDeclBuilder {
       return;
     }
 
-    Record = CXXRecordDecl::Create(AST, TagDecl::TagKind::TTK_Class,
-                                   HLSLNamespace, SourceLocation(),
-                                   SourceLocation(), &II, PrevDecl, true);
+    Record = CXXRecordDecl::Create(AST, TagDecl::TagKind::Class, HLSLNamespace,
+                                   SourceLocation(), SourceLocation(), &II,
+                                   PrevDecl, true);
     Record->setImplicit(true);
     Record->setLexicalDeclContext(HLSLNamespace);
     Record->setHasExternalLexicalStorage();
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 8e78d2c11f92d..d25edd470334f 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -329,8 +329,9 @@ void Sema::Initialize() {
   if (getLangOpts().MSVCCompat) {
     if (getLangOpts().CPlusPlus &&
         IdResolver.begin(&Context.Idents.get("type_info")) == IdResolver.end())
-      PushOnScopeChains(Context.buildImplicitRecord("type_info", TTK_Class),
-                        TUScope);
+      PushOnScopeChains(
+          Context.buildImplicitRecord("type_info", TagTypeKind::Class),
+          TUScope);
 
     addImplicitTypedef("size_t", Context.getSizeType());
   }
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index adb82d3f6d176..3355336d8c2c8 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -1576,8 +1576,9 @@ bool ResultBuilder::IsClassOrStruct(const NamedDecl *ND) const {
 
   // For purposes of this check, interfaces match too.
   if (const auto *RD = dyn_cast<RecordDecl>(ND))
-    return RD->getTagKind() == TTK_Class || RD->getTagKind() == TTK_Struct ||
-           RD->getTagKind() == TTK_Interface;
+    return RD->getTagKind() == TagTypeKind::Class ||
+           RD->getTagKind() == TagTypeKind::Struct ||
+           RD->getTagKind() == TagTypeKind::Interface;
 
   return false;
 }
@@ -1589,7 +1590,7 @@ bool ResultBuilder::IsUnion(const NamedDecl *ND) const {
     ND = ClassTemplate->getTemplatedDecl();
 
   if (const auto *RD = dyn_cast<RecordDecl>(ND))
-    return RD->getTagKind() == TTK_Union;
+    return RD->getTagKind() == TagTypeKind::Union;
 
   return false;
 }
@@ -2018,15 +2019,15 @@ static const char *GetCompletionTypeString(QualType T, ASTContext &Context,
       if (TagDecl *Tag = TagT->getDecl())
         if (!Tag->hasNameForLinkage()) {
           switch (Tag->getTagKind()) {
-          case TTK_Struct:
+          case TagTypeKind::Struct:
             return "struct <anonymous>";
-          case TTK_Interface:
+          case TagTypeKind::Interface:
             return "__interface <anonymous>";
-          case TTK_Class:
+          case TagTypeKind::Class:
             return "class <anonymous>";
-          case TTK_Union:
+          case TagTypeKind::Union:
             return "union <anonymous>";
-          case TTK_Enum:
+          case TagTypeKind::Enum:
             return "enum <anonymous>";
           }
         }
@@ -4167,14 +4168,14 @@ CXCursorKind clang::getCursorKindForDecl(const Decl *D) {
   default:
     if (const auto *TD = dyn_cast<TagDecl>(D)) {
       switch (TD->getTagKind()) {
-      case TTK_Interface: // fall through
-      case TTK_Struct:
+      case TagTypeKind::Interface: // fall through
+      case TagTypeKind::Struct:
         return CXCursor_StructDecl;
-      case TTK_Class:
+      case TagTypeKind::Class:
         return CXCursor_ClassDecl;
-      case TTK_Union:
+      case TagTypeKind::Union:
         return CXCursor_UnionDecl;
-      case TTK_Enum:
+      case TagTypeKind::Enum:
         return CXCursor_EnumDecl;
       }
     }
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index b4affa7277f6b..396566a8f10a9 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -680,11 +680,16 @@ DeclSpec::TST Sema::isTagName(IdentifierInfo &II, Scope *S) {
   if (R.getResultKind() == LookupResult::Found)
     if (const TagDecl *TD = R.getAsSingle<TagDecl>()) {
       switch (TD->getTagKind()) {
-      case TTK_Struct: return DeclSpec::TST_struct;
-      case TTK_Interface: return DeclSpec::TST_interface;
-      case TTK_Union:  return DeclSpec::TST_union;
-      case TTK_Class:  return DeclSpec::TST_class;
-      case TTK_Enum:   return DeclSpec::TST_enum;
+      case TagTypeKind::Struct:
+        return DeclSpec::TST_struct;
+      case TagTypeKind::Interface:
+        return DeclSpec::TST_interface;
+      case TagTypeKind::Union:
+        return DeclSpec::TST_union;
+      case TagTypeKind::Class:
+        return DeclSpec::TST_class;
+      case TagTypeKind::Enum:
+        return DeclSpec::TST_enum;
       }
     }
 
@@ -860,25 +865,25 @@ static bool isTagTypeWithMissingTag(Sema &SemaRef, LookupResult &Result,
   if (TagDecl *Tag = R.getAsSingle<TagDecl>()) {
     StringRef FixItTagName;
     switch (Tag->getTagKind()) {
-      case TTK_Class:
-        FixItTagName = "class ";
-        break;
+    case TagTypeKind::Class:
+      FixItTagName = "class ";
+      break;
 
-      case TTK_Enum:
-        FixItTagName = "enum ";
-        break;
+    case TagTypeKind::Enum:
+      FixItTagName = "enum ";
+      break;
 
-      case TTK_Struct:
-        FixItTagName = "struct ";
-        break;
+    case TagTypeKind::Struct:
+      FixItTagName = "struct ";
+      break;
 
-      case TTK_Interface:
-        FixItTagName = "__interface ";
-        break;
+    case TagTypeKind::Interface:
+      FixItTagName = "__interface ";
+      break;
 
-      case TTK_Union:
-        FixItTagName = "union ";
-        break;
+    case TagTypeKind::Union:
+      FixItTagName = "union ";
+      break;
     }
 
     StringRef TagName = FixItTagName.drop_back();
@@ -5268,8 +5273,8 @@ Decl *Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS,
   if (DS.isModulePrivateSpecified() &&
       Tag && Tag->getDeclContext()->isFunctionOrMethod())
     Diag(DS.getModulePrivateSpecLoc(), diag::err_module_private_local_class)
-      << Tag->getTagKind()
-      << FixItHint::CreateRemoval(DS.getModulePrivateSpecLoc());
+        << llvm::to_underlying(Tag->getTagKind())
+        << FixItHint::CreateRemoval(DS.getModulePrivateSpecLoc());
 
   ActOnDocumentableDecl(TagD);
 
@@ -7667,14 +7672,15 @@ NamedDecl *Sema::ActOnVariableDeclarator(
           // members.
           Diag(D.getIdentifierLoc(),
                diag::err_static_data_member_not_allowed_in_local_class)
-            << Name << RD->getDeclName() << RD->getTagKind();
+              << Name << RD->getDeclName()
+              << llvm::to_underlying(RD->getTagKind());
         } else if (AnonStruct) {
           // C++ [class.static.data]p4: Unnamed classes and classes contained
           // directly or indirectly within unnamed classes shall not contain
           // static data members.
           Diag(D.getIdentifierLoc(),
                diag::err_static_data_member_not_allowed_in_anon_struct)
-            << Name << AnonStruct->getTagKind();
+              << Name << llvm::to_underlying(AnonStruct->getTagKind());
           Invalid = true;
         } else if (RD->isUnion()) {
           // C++98 [class.union]p1: If a union contains a static data member,
@@ -16766,9 +16772,12 @@ bool Sema::CheckEnumRedeclaration(SourceLocation EnumLoc, bool IsScoped,
 /// \returns diagnostic %select index.
 static unsigned getRedeclDiagFromTagKind(TagTypeKind Tag) {
   switch (Tag) {
-  case TTK_Struct: return 0;
-  case TTK_Interface: return 1;
-  case TTK_Class:  return 2;
+  case TagTypeKind::Struct:
+    return 0;
+  case TagTypeKind::Interface:
+    return 1;
+  case TagTypeKind::Class:
+    return 2;
   default: llvm_unreachable("Invalid tag kind for redecl diagnostic!");
   }
 }
@@ -16779,7 +16788,8 @@ static unsigned getRedeclDiagFromTagKind(TagTypeKind Tag) {
 /// \returns true iff the tag kind is compatible.
 static bool isClassCompatTagKind(TagTypeKind Tag)
 {
-  return Tag == TTK_Struct || Tag == TTK_Class || Tag == TTK_Interface;
+  return Tag == TagTypeKind::Struct || Tag == TagTypeKind::Class ||
+         Tag == TagTypeKind::Interface;
 }
 
 Sema::NonTagKind Sema::getNonTagTypeDeclKind(const Decl *PrevDecl,
@@ -16795,13 +16805,13 @@ Sema::NonTagKind Sema::getNonTagTypeDeclKind(const Decl *PrevDecl,
   else if (isa<TemplateTemplateParmDecl>(PrevDecl))
     return NTK_TemplateTemplateArgument;
   switch (TTK) {
-  case TTK_Struct:
-  case TTK_Interface:
-  case TTK_Class:
+  case TagTypeKind::Struct:
+  case TagTypeKind::Interface:
+  case TagTypeKind::Class:
     return getLangOpts().CPlusPlus ? NTK_NonClass : NTK_NonStruct;
-  case TTK_Union:
+  case TagTypeKind::Union:
     return NTK_NonUnion;
-  case TTK_Enum:
+  case TagTypeKind::Enum:
     return NTK_NonEnum;
   }
   llvm_unreachable("invalid TTK");
@@ -17037,7 +17047,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
             MatchTemplateParametersToScopeSpecifier(
                 KWLoc, NameLoc, SS, nullptr, TemplateParameterLists,
                 TUK == TUK_Friend, isMemberSpecialization, Invalid)) {
-      if (Kind == TTK_Enum) {
+      if (Kind == TagTypeKind::Enum) {
         Diag(KWLoc, diag::err_enum_template);
         return true;
       }
@@ -17075,7 +17085,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
   llvm::PointerUnion<const Type*, TypeSourceInfo*> EnumUnderlying;
   bool IsFixed = !UnderlyingType.isUnset() || ScopedEnum;
 
-  if (Kind == TTK_Enum) {
+  if (Kind == TagTypeKind::Enum) {
     if (UnderlyingType.isInvalid() || (!UnderlyingType.get() && ScopedEnum)) {
       // No underlying type explicitly specified, or we failed to parse the
       // type, default to int.
@@ -17125,7 +17135,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     SourceLocation Loc = NameLoc.isValid() ? NameLoc : KWLoc;
     TagDecl *New = nullptr;
 
-    if (Kind == TTK_Enum) {
+    if (Kind == TagTypeKind::Enum) {
       New = EnumDecl::Create(Context, SearchDC, KWLoc, Loc, Name, nullptr,
                              ScopedEnum, ScopedEnumUsesClassTag, IsFixed);
       // If this is an undefined enum, bail.
@@ -17218,7 +17228,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
 
       // A tag 'foo::bar' must already exist.
       Diag(NameLoc, diag::err_not_tag_in_scope)
-        << Kind << Name << DC << SS.getRange();
+          << llvm::to_underlying(Kind) << Name << DC << SS.getRange();
       Name = nullptr;
       Invalid = true;
       goto CreateNewDecl;
@@ -17478,9 +17488,9 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
         if (!isAcceptableTagRedeclaration(PrevTagDecl, Kind,
                                           TUK == TUK_Definition, KWLoc,
                                           Name)) {
-          bool SafeToContinue
-            = (PrevTagDecl->getTagKind() != TTK_Enum &&
-               Kind != TTK_Enum);
+          bool SafeToContinue =
+              (PrevTagDecl->getTagKind() != TagTypeKind::Enum &&
+               Kind != TagTypeKind::Enum);
           if (SafeToContinue)
             Diag(KWLoc, diag::err_use_with_wrong_tag)
               << Name
@@ -17500,7 +17510,8 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
           }
         }
 
-        if (Kind == TTK_Enum && PrevTagDecl->getTagKind() == TTK_Enum) {
+        if (Kind == TagTypeKind::Enum &&
+            PrevTagDecl->getTagKind() == TagTypeKind::Enum) {
           const EnumDecl *PrevEnum = cast<EnumDecl>(PrevTagDecl);
           if (TUK == TUK_Reference || TUK == TUK_Friend)
             return PrevTagDecl;
@@ -17670,8 +17681,8 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       if ((TUK == TUK_Reference || TUK == TUK_Friend) &&
           !Previous.isForRedeclaration()) {
         NonTagKind NTK = getNonTagTypeDeclKind(PrevDecl, Kind);
-        Diag(NameLoc, diag::err_tag_reference_non_tag) << PrevDecl << NTK
-                                                       << Kind;
+        Diag(NameLoc, diag::err_tag_reference_non_tag)
+            << PrevDecl << NTK << llvm::to_underlying(Kind);
         Diag(PrevDecl->getLocation(), diag::note_declared_at);
         Invalid = true;
 
@@ -17729,7 +17740,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
   // PrevDecl.
   TagDecl *New;
 
-  if (Kind == TTK_Enum) {
+  if (Kind == TagTypeKind::Enum) {
     // FIXME: Tag decls should be chained to any simultaneous vardecls, e.g.:
     // enum X { A, B, C } D;    D should chain to X.
     New = EnumDecl::Create(Context, SearchDC, KWLoc, Loc, Name,
@@ -17864,7 +17875,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
   // If we're declaring or defining a tag in function prototype scope in C,
   // note that this type can only be used within the function and add it to
   // the list of decls to inject into the function definition scope.
-  if ((Name || Kind == TTK_Enum) &&
+  if ((Name || Kind == TagTypeKind::Enum) &&
       getNonFieldDeclScope(S)->isFunctionPrototypeScope()) {
     if (getLangOpts().CPlusPlus) {
       // C++ [dcl.fct]p6:
@@ -19038,7 +19049,8 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
         unsigned DiagID = 0;
         if (!Record->isUnion() && !IsLastField) {
           Diag(FD->getLocation(), diag::err_flexible_array_not_at_end)
-            << FD->getDeclName() << FD->getType() << Record->getTagKind();
+              << FD->getDeclName() << FD->getType()
+              << llvm::to_underlying(Record->getTagKind());
           Diag((*(i + 1))->getLocation(), diag::note_next_field_declaration);
           FD->setInvalidDecl();
           EnclosingDecl->setInvalidDecl();
@@ -19057,8 +19069,8 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
                              : diag::err_flexible_array_empty_aggregate;
 
         if (DiagID)
-          Diag(FD->getLocation(), DiagID) << FD->getDeclName()
-                                          << Record->getTagKind();
+          Diag(FD->getLocation(), DiagID)
+              << FD->getDeclName() << llvm::to_underlying(Record->getTagKind());
         // While the layout of types that contain virtual bases is not specified
         // by the C++ standard, both the Itanium and Microsoft C++ ABIs place
         // virtual bases after the derived members.  This would make a flexible
@@ -19066,10 +19078,10 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
         // of the type.
         if (CXXRecord && CXXRecord->getNumVBases() != 0)
           Diag(FD->getLocation(), diag::err_flexible_array_virtual_base)
-              << FD->getDeclName() << Record->getTagKind();
+              << FD->getDeclName() << llvm::to_underlying(Record->getTagKind());
         if (!getLangOpts().C99)
           Diag(FD->getLocation(), diag::ext_c99_flexible_array_member)
-            << FD->getDeclName() << Record->getTagKind();
+              << FD->getDeclName() << llvm::to_underlying(Record->getTagKind());
 
         // If the element type has a non-trivial destructor, we would not
         // implicitly destroy the elements, so disallow it for now.
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 842a01a88cd3c..cdb769a883550 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -189,7 +189,7 @@ static inline bool isCFStringType(QualType T, ASTContext &Ctx) {
     return false;
 
   const RecordDecl *RD = RT->getDecl();
-  if (RD->getTagKind() != TTK_Struct)
+  if (RD->getTagKind() != TagTypeKind::Struct)
     return false;
 
   return RD->getIdentifier() == &Ctx.Idents.get("__CFString");
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index be79defbbfac6..397b7a00e4531 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -1781,9 +1781,12 @@ static bool CheckConstexprReturnType(Sema &SemaRef, const FunctionDecl *FD,
 /// \returns diagnostic %select index.
 static unsigned getRecordDiagFromTagKind(TagTypeKind Tag) {
   switch (Tag) {
-  case TTK_Struct: return 0;
-  case TTK_Interface: return 1;
-  case TTK_Class:  return 2;
+  case TagTypeKind::Struct:
+    return 0;
+  case TagTypeKind::Interface:
+    return 1;
+  case TagTypeKind::Class:
+    return 2;
   default: llvm_unreachable("Invalid tag kind for record diagnostic!");
   }
 }
@@ -2680,7 +2683,7 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
                          TypeSourceInfo *TInfo,
                          SourceLocation EllipsisLoc) {
   // In HLSL, unspecified class access is public rather than private.
-  if (getLangOpts().HLSL && Class->getTagKind() == TTK_Class &&
+  if (getLangOpts().HLSL && Class->getTagKind() == TagTypeKind::Class &&
       Access == AS_none)
     Access = AS_public;
 
@@ -2733,9 +2736,9 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
     // emitted.
     if (!Class->getTypeForDecl()->isDependentType())
       Class->setInvalidDecl();
-    return new (Context) CXXBaseSpecifier(SpecifierRange, Virtual,
-                                          Class->getTagKind() == TTK_Class,
-                                          Access, TInfo, EllipsisLoc);
+    return new (Context) CXXBaseSpecifier(
+        SpecifierRange, Virtual, Class->getTagKind() == TagTypeKind::Class,
+        Access, TInfo, EllipsisLoc);
   }
 
   // Base specifiers must be record types.
@@ -2821,9 +2824,9 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
     Class->setInvalidDecl();
 
   // Create the base specifier.
-  return new (Context) CXXBaseSpecifier(SpecifierRange, Virtual,
-                                        Class->getTagKind() == TTK_Class,
-                                        Access, TInfo, EllipsisLoc);
+  return new (Context) CXXBaseSpecifier(
+      SpecifierRange, Virtual, Class->getTagKind() == TagTypeKind::Class,
+      Access, TInfo, EllipsisLoc);
 }
 
 /// ActOnBaseSpecifier - Parsed a base specifier. A base specifier is
@@ -7010,7 +7013,7 @@ void Sema::CheckCompletedCXXClass(Scope *S, CXXRecordDecl *Record) {
           (F->getType().isConstQualified() && F->getType()->isScalarType())) {
         if (!Complained) {
           Diag(Record->getLocation(), diag::warn_no_constructor_for_refconst)
-            << Record->getTagKind() << Record;
+              << llvm::to_underlying(Record->getTagKind()) << Record;
           Complained = true;
         }
 
diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index 8685838157b5c..cdfa6ad3f281a 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -3884,7 +3884,7 @@ static void DiagnoseVariableSizedIvars(Sema &S, ObjCContainerDecl *OCD) {
     if (IvarTy->isIncompleteArrayType()) {
       S.Diag(ivar->getLocation(), diag::err_flexible_array_not_at_end)
           << ivar->getDeclName() << IvarTy
-          << TTK_Class; // Use "class" for Obj-C.
+          << llvm::to_underlying(TagTypeKind::Class); // Use "class" for Obj-C.
       IsInvalidIvar = true;
     } else if (const RecordType *RecordTy = IvarTy->getAs<RecordType>()) {
       if (RecordTy->getDecl()->hasFlexibleArrayMember()) {
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index ea286c9709c13..093c57d64a712 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -3035,11 +3035,10 @@ void Sema::DeclareGlobalNewDelete() {
   if (!StdBadAlloc && !getLangOpts().CPlusPlus11) {
     // The "std::bad_alloc" class has not yet been declared, so build it
     // implicitly.
-    StdBadAlloc = CXXRecordDecl::Create(Context, TTK_Class,
-                                        getOrCreateStdNamespace(),
-                                        SourceLocation(), SourceLocation(),
-                                      &PP.getIdentifierTable().get("bad_alloc"),
-                                        nullptr);
+    StdBadAlloc = CXXRecordDecl::Create(
+        Context, TagTypeKind::Class, getOrCreateStdNamespace(),
+        SourceLocation(), SourceLocation(),
+        &PP.getIdentifierTable().get("bad_alloc"), nullptr);
     getStdBadAlloc()->setImplicit(true);
 
     // The implicitly declared "std::bad_alloc" should live in global module
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 333226963aeac..5ef0aaa40ba1f 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -4692,10 +4692,11 @@ Sema::CreateCapturedStmtRecordDecl(CapturedDecl *&CD, SourceLocation Loc,
 
   RecordDecl *RD = nullptr;
   if (getLangOpts().CPlusPlus)
-    RD = CXXRecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc,
+    RD = CXXRecordDecl::Create(Context, TagTypeKind::Struct, DC, Loc, Loc,
                                /*Id=*/nullptr);
   else
-    RD = RecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc, /*Id=*/nullptr);
+    RD = RecordDecl::Create(Context, TagTypeKind::Struct, DC, Loc, Loc,
+                            /*Id=*/nullptr);
 
   RD->setCapturedRecord();
   DC->addDecl(RD);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 4d6b2376ba786..ee35486221280 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1841,7 +1841,8 @@ DeclResult Sema::CheckClassTemplate(
     return true;
 
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
-  assert(Kind != TTK_Enum && "can't build template of enumerated type");
+  assert(Kind != TagTypeKind::Enum &&
+         "can't build template of enumerated type");
 
   // There is no such thing as an unnamed class template.
   if (!Name) {
@@ -4292,7 +4293,7 @@ TypeResult Sema::ActOnTagTemplateIdType(TagUseKind TUK,
     //   resolves to an alias template specialization, the
     //   elaborated-type-specifier is ill-formed.
     Diag(TemplateLoc, diag::err_tag_reference_non_tag)
-        << TAT << NTK_TypeAliasTemplate << TagKind;
+        << TAT << NTK_TypeAliasTemplate << llvm::to_underlying(TagKind);
     Diag(TAT->getLocation(), diag::note_declared_at);
   }
 
@@ -8722,7 +8723,8 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   // Check that the specialization uses the same tag kind as the
   // original template.
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
-  assert(Kind != TTK_Enum && "Invalid enum tag in class template spec!");
+  assert(Kind != TagTypeKind::Enum &&
+         "Invalid enum tag in class template spec!");
   if (!isAcceptableTagRedeclaration(ClassTemplate->getTemplatedDecl(),
                                     Kind, TUK == TUK_Definition, KWLoc,
                                     ClassTemplate->getIdentifier())) {
@@ -9968,14 +9970,15 @@ DeclResult Sema::ActOnExplicitInstantiation(
   // Check that the specialization uses the same tag kind as the
   // original template.
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
-  assert(Kind != TTK_Enum &&
+  assert(Kind != TagTypeKind::Enum &&
          "Invalid enum tag in class template explicit instantiation!");
 
   ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(TD);
 
   if (!ClassTemplate) {
     NonTagKind NTK = getNonTagTypeDeclKind(TD, Kind);
-    Diag(TemplateNameLoc, diag::err_tag_reference_non_tag) << TD << NTK << Kind;
+    Diag(TemplateNameLoc, diag::err_tag_reference_non_tag)
+        << TD << NTK << llvm::to_underlying(Kind);
     Diag(TD->getLocation(), diag::note_previous_use);
     return true;
   }
@@ -10800,7 +10803,8 @@ Sema::ActOnDependentTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
 
   if (TUK == TUK_Declaration || TUK == TUK_Definition) {
     Diag(NameLoc, diag::err_dependent_tag_decl)
-      << (TUK == TUK_Definition) << Kind << SS.getRange();
+        << (TUK == TUK_Definition) << llvm::to_underlying(Kind)
+        << SS.getRange();
     return true;
   }
 
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 8edcbf4709a23..011356e08a042 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1662,8 +1662,8 @@ Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
 
     if (!PrevClassTemplate && QualifierLoc) {
       SemaRef.Diag(Pattern->getLocation(), diag::err_not_tag_in_scope)
-        << D->getTemplatedDecl()->getTagKind() << Pattern->getDeclName() << DC
-        << QualifierLoc.getSourceRange();
+          << llvm::to_underlying(D->getTemplatedDecl()->getTagKind())
+          << Pattern->getDeclName() << DC << QualifierLoc.getSourceRange();
       return nullptr;
     }
   }
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index a46deed8e7c58..560feafa1857c 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -3667,11 +3667,20 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
         Error = 6; // Interface member.
       } else {
         switch (cast<TagDecl>(SemaRef.CurContext)->getTagKind()) {
-        case TTK_Enum: llvm_unreachable("unhandled tag kind");
-        case TTK_Struct: Error = Cxx ? 1 : 2; /* Struct member */ break;
-        case TTK_Union:  Error = Cxx ? 3 : 4; /* Union member */ break;
-        case TTK_Class:  Error = 5; /* Class member */ break;
-        case TTK_Interface: Error = 6; /* Interface member */ break;
+        case TagTypeKind::Enum:
+          llvm_unreachable("unhandled tag kind");
+        case TagTypeKind::Struct:
+          Error = Cxx ? 1 : 2; /* Struct member */
+          break;
+        case TagTypeKind::Union:
+          Error = Cxx ? 3 : 4; /* Union member */
+          break;
+        case TagTypeKind::Class:
+          Error = 5; /* Class member */
+          break;
+        case TagTypeKind::Interface:
+          Error = 6; /* Interface member */
+          break;
         }
       }
       if (D.getDeclSpec().isFriendSpecified())
@@ -4413,7 +4422,7 @@ bool Sema::isCFError(RecordDecl *RD) {
   // NSError. CFErrorRef used to be declared with "objc_bridge" but is now
   // declared with "objc_bridge_mutable", so look for either one of the two
   // attributes.
-  if (RD->getTagKind() == TTK_Struct) {
+  if (RD->getTagKind() == TagTypeKind::Struct) {
     IdentifierInfo *bridgedType = nullptr;
     if (auto bridgeAttr = RD->getAttr<ObjCBridgeAttr>())
       bridgedType = bridgeAttr->getBridgedType();
@@ -9417,9 +9426,12 @@ bool Sema::RequireCompleteType(SourceLocation Loc, QualType T,
 /// \returns diagnostic %select index.
 static unsigned getLiteralDiagFromTagKind(TagTypeKind Tag) {
   switch (Tag) {
-  case TTK_Struct: return 0;
-  case TTK_Interface: return 1;
-  case TTK_Class:  return 2;
+  case TagTypeKind::Struct:
+    return 0;
+  case TagTypeKind::Interface:
+    return 1;
+  case TagTypeKind::Class:
+    return 2;
   default: llvm_unreachable("Invalid tag kind for literal type diagnostic!");
   }
 }
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 22357d55d3733..ac12b39a5978b 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -1209,14 +1209,15 @@ class TreeTransform {
         case LookupResult::FoundUnresolvedValue: {
           NamedDecl *SomeDecl = Result.getRepresentativeDecl();
           Sema::NonTagKind NTK = SemaRef.getNonTagTypeDeclKind(SomeDecl, Kind);
-          SemaRef.Diag(IdLoc, diag::err_tag_reference_non_tag) << SomeDecl
-                                                               << NTK << Kind;
+          SemaRef.Diag(IdLoc, diag::err_tag_reference_non_tag)
+              << SomeDecl << NTK << llvm::to_underlying(Kind);
           SemaRef.Diag(SomeDecl->getLocation(), diag::note_declared_at);
           break;
         }
         default:
           SemaRef.Diag(IdLoc, diag::err_not_tag_in_scope)
-              << Kind << Id << DC << QualifierLoc.getSourceRange();
+              << llvm::to_underlying(Kind) << Id << DC
+              << QualifierLoc.getSourceRange();
           break;
       }
       return QualType();
@@ -7029,7 +7030,8 @@ TreeTransform<Derived>::TransformElaboratedType(TypeLocBuilder &TLB,
         SemaRef.Diag(TL.getNamedTypeLoc().getBeginLoc(),
                      diag::err_tag_reference_non_tag)
             << TAT << Sema::NTK_TypeAliasTemplate
-            << ElaboratedType::getTagTypeKindForKeyword(T->getKeyword());
+            << llvm::to_underlying(
+                   ElaboratedType::getTagTypeKindForKeyword(T->getKeyword()));
         SemaRef.Diag(TAT->getLocation(), diag::note_declared_at);
       }
     }
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index a63911cb4adfb..79817b3fb1ec3 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -757,7 +757,8 @@ ASTDeclReader::RedeclarableResult ASTDeclReader::VisitTagDecl(TagDecl *TD) {
   TD->IdentifierNamespace = Record.readInt();
 
   BitsUnpacker TagDeclBits(Record.readInt());
-  TD->setTagKind((TagDecl::TagKind)TagDeclBits.getNextBits(/*Width=*/3));
+  TD->setTagKind(
+      static_cast<TagTypeKind>(TagDeclBits.getNextBits(/*Width=*/3)));
   TD->setCompleteDefinition(TagDeclBits.getNextBit());
   TD->setEmbeddedInDeclarator(TagDeclBits.getNextBit());
   TD->setFreeStanding(TagDeclBits.getNextBit());
@@ -4587,7 +4588,7 @@ void ASTDeclReader::UpdateDecl(Decl *D,
         }
       }
 
-      RD->setTagKind((TagTypeKind)Record.readInt());
+      RD->setTagKind(static_cast<TagTypeKind>(Record.readInt()));
       RD->setLocation(readSourceLocation());
       RD->setLocStart(readSourceLocation());
       RD->setBraceRange(readSourceRange());
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 2fe12f7ff300f..1e86566d81fbc 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -5333,7 +5333,7 @@ void ASTWriter::WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord) {
             Record.push_back(false);
           }
         }
-        Record.push_back(RD->getTagKind());
+        Record.push_back(llvm::to_underlying(RD->getTagKind()));
         Record.AddSourceLocation(RD->getLocation());
         Record.AddSourceLocation(RD->getBeginLoc());
         Record.AddSourceRange(RD->getBraceRange());
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index b4438e4cf6a0c..a06df18e89818 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -445,7 +445,7 @@ void ASTDeclWriter::VisitTagDecl(TagDecl *D) {
   Record.push_back(D->getIdentifierNamespace());
 
   BitsPacker TagDeclBits;
-  TagDeclBits.addBits(D->getTagKind(), /*BitWidth=*/3);
+  TagDeclBits.addBits(llvm::to_underlying(D->getTagKind()), /*BitWidth=*/3);
   TagDeclBits.addBit(!isa<CXXRecordDecl>(D) ? D->isCompleteDefinition() : 0);
   TagDeclBits.addBit(D->isEmbeddedInDeclarator());
   TagDeclBits.addBit(D->isFreeStanding());
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp
index 66d8588e25315..d10924776f107 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/NoUncountedMembersChecker.cpp
@@ -104,7 +104,7 @@ class NoUncountedMemberChecker
 
     const auto Kind = RD->getTagKind();
     // FIMXE: Should we check union members too?
-    if (Kind != TTK_Struct && Kind != TTK_Class)
+    if (Kind != TagTypeKind::Struct && Kind != TagTypeKind::Class)
       return true;
 
     // Ignore CXXRecords that come from system headers.
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp
index 48dcfc4a3c464..bd7c50ccfa9c4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/RefCntblBaseVirtualDtorChecker.cpp
@@ -114,7 +114,7 @@ class RefCntblBaseVirtualDtorChecker
       return true;
 
     const auto Kind = RD->getTagKind();
-    if (Kind != TTK_Struct && Kind != TTK_Class)
+    if (Kind != TagTypeKind::Struct && Kind != TagTypeKind::Class)
       return true;
 
     // Ignore CXXRecords that come from system headers.
diff --git a/clang/tools/libclang/CIndexCXX.cpp b/clang/tools/libclang/CIndexCXX.cpp
index a06fe7ba4af56..ea6f97d39644e 100644
--- a/clang/tools/libclang/CIndexCXX.cpp
+++ b/clang/tools/libclang/CIndexCXX.cpp
@@ -63,11 +63,15 @@ enum CXCursorKind clang_getTemplateCursorKind(CXCursor C) {
           = dyn_cast_or_null<ClassTemplatePartialSpecializationDecl>(
                                                             getCursorDecl(C))) {
       switch (PartialSpec->getTagKind()) {
-      case TTK_Interface:
-      case TTK_Struct: return CXCursor_StructDecl;
-      case TTK_Class: return CXCursor_ClassDecl;
-      case TTK_Union: return CXCursor_UnionDecl;
-      case TTK_Enum: return CXCursor_NoDeclFound;
+      case TagTypeKind::Interface:
+      case TagTypeKind::Struct:
+        return CXCursor_StructDecl;
+      case TagTypeKind::Class:
+        return CXCursor_ClassDecl;
+      case TagTypeKind::Union:
+        return CXCursor_UnionDecl;
+      case TagTypeKind::Enum:
+        return CXCursor_NoDeclFound;
       }
     }
     break;
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 0cbec5cf9ba06..5f4d8d040772c 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -7705,8 +7705,9 @@ TEST_P(ImportWithExternalSource, CompleteRecordBeforeImporting) {
 
   // Create a dummy class by hand with external lexical storage.
   IdentifierInfo &Ident = Context.Idents.get("test_class");
-  auto *Record = CXXRecordDecl::Create(
-      Context, TTK_Class, FromTU, SourceLocation(), SourceLocation(), &Ident);
+  auto *Record =
+      CXXRecordDecl::Create(Context, TagTypeKind::Class, FromTU,
+                            SourceLocation(), SourceLocation(), &Ident);
   Record->setHasExternalLexicalStorage();
   FromTU->addDecl(Record);
 
diff --git a/clang/utils/ClangVisualizers/clang.natvis b/clang/utils/ClangVisualizers/clang.natvis
index cbb63dc08de23..2d1ad16797f81 100644
--- a/clang/utils/ClangVisualizers/clang.natvis
+++ b/clang/utils/ClangVisualizers/clang.natvis
@@ -347,11 +347,11 @@ For later versions of Visual Studio, no setup is required-->
     <DisplayString IncludeView="implicit"></DisplayString>
     <DisplayString IncludeView="modifiers">{*this,view(implicit)nd}</DisplayString>
     <DisplayString IncludeView="cpp">{*this,view(modifiers)}{Name,view(cpp)}</DisplayString>
-    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::TTK_Struct">{*this,view(modifiers)nd}struct {Name,view(cpp)}</DisplayString>
-    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::TTK_Interface">{*this,view(modifiers)nd}interface {Name,view(cpp)}</DisplayString>
-    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::TTK_Union">{*this,view(modifiers)nd}union {Name,view(cpp)}</DisplayString>
-    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::TTK_Class">{*this,view(modifiers)nd}class {Name,view(cpp)}</DisplayString>
-    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::TTK_Enum">{*this,view(modifiers)nd}enum {Name,view(cpp)}</DisplayString>
+    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::Struct">{*this,view(modifiers)nd}struct {Name,view(cpp)}</DisplayString>
+    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::Interface">{*this,view(modifiers)nd}interface {Name,view(cpp)}</DisplayString>
+    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::Union">{*this,view(modifiers)nd}union {Name,view(cpp)}</DisplayString>
+    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::Class">{*this,view(modifiers)nd}class {Name,view(cpp)}</DisplayString>
+    <DisplayString Condition="TagDeclBits.TagDeclKind==clang::TagTypeKind::Enum">{*this,view(modifiers)nd}enum {Name,view(cpp)}</DisplayString>
     <Expand>
       <ExpandedItem>(clang::DeclContext *)this</ExpandedItem>
     </Expand>
diff --git a/lldb/source/Plugins/Language/ObjC/NSDictionary.cpp b/lldb/source/Plugins/Language/ObjC/NSDictionary.cpp
index 2e927eb8d8569..605c79cbd9b55 100644
--- a/lldb/source/Plugins/Language/ObjC/NSDictionary.cpp
+++ b/lldb/source/Plugins/Language/ObjC/NSDictionary.cpp
@@ -78,7 +78,8 @@ static CompilerType GetLLDBNSPairType(TargetSP target_sp) {
   if (!compiler_type) {
     compiler_type = scratch_ts_sp->CreateRecordType(
         nullptr, OptionalClangModuleID(), lldb::eAccessPublic,
-        g_lldb_autogen_nspair, clang::TTK_Struct, lldb::eLanguageTypeC);
+        g_lldb_autogen_nspair, llvm::to_underlying(clang::TagTypeKind::Struct),
+        lldb::eLanguageTypeC);
 
     if (compiler_type) {
       TypeSystemClang::StartTagDeclarationDefinition(compiler_type);
diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTypeEncodingParser.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTypeEncodingParser.cpp
index 2cc5319c84bbe..ca582cb1d5a46 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTypeEncodingParser.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTypeEncodingParser.cpp
@@ -81,13 +81,13 @@ AppleObjCTypeEncodingParser::ReadStructElement(TypeSystemClang &ast_ctx,
 clang::QualType AppleObjCTypeEncodingParser::BuildStruct(
     TypeSystemClang &ast_ctx, StringLexer &type, bool for_expression) {
   return BuildAggregate(ast_ctx, type, for_expression, _C_STRUCT_B, _C_STRUCT_E,
-                        clang::TTK_Struct);
+                        llvm::to_underlying(clang::TagTypeKind::Struct));
 }
 
 clang::QualType AppleObjCTypeEncodingParser::BuildUnion(
     TypeSystemClang &ast_ctx, StringLexer &type, bool for_expression) {
   return BuildAggregate(ast_ctx, type, for_expression, _C_UNION_B, _C_UNION_E,
-                        clang::TTK_Union);
+                        llvm::to_underlying(clang::TagTypeKind::Union));
 }
 
 clang::QualType AppleObjCTypeEncodingParser::BuildAggregate(
diff --git a/lldb/source/Plugins/Platform/FreeBSD/PlatformFreeBSD.cpp b/lldb/source/Plugins/Platform/FreeBSD/PlatformFreeBSD.cpp
index 7abc71a1c53fe..d7584be2b95ee 100644
--- a/lldb/source/Plugins/Platform/FreeBSD/PlatformFreeBSD.cpp
+++ b/lldb/source/Plugins/Platform/FreeBSD/PlatformFreeBSD.cpp
@@ -206,7 +206,7 @@ CompilerType PlatformFreeBSD::GetSiginfoType(const llvm::Triple &triple) {
 
   CompilerType sigval_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "__lldb_sigval_t",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(sigval_type);
   ast->AddFieldToRecordType(sigval_type, "sival_int", int_type,
                             lldb::eAccessPublic, 0);
@@ -217,7 +217,7 @@ CompilerType PlatformFreeBSD::GetSiginfoType(const llvm::Triple &triple) {
   // siginfo_t
   CompilerType siginfo_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "__lldb_siginfo_t",
-      clang::TTK_Struct, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Struct), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(siginfo_type);
   ast->AddFieldToRecordType(siginfo_type, "si_signo", int_type,
                             lldb::eAccessPublic, 0);
@@ -239,7 +239,7 @@ CompilerType PlatformFreeBSD::GetSiginfoType(const llvm::Triple &triple) {
   // union used to hold the signal data
   CompilerType union_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(union_type);
 
   ast->AddFieldToRecordType(
diff --git a/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp b/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
index dd50bfc2dc04a..13465986f49c5 100644
--- a/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
+++ b/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
@@ -348,7 +348,7 @@ CompilerType PlatformLinux::GetSiginfoType(const llvm::Triple &triple) {
 
   CompilerType sigval_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "__lldb_sigval_t",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(sigval_type);
   ast->AddFieldToRecordType(sigval_type, "sival_int", int_type,
                             lldb::eAccessPublic, 0);
@@ -358,7 +358,7 @@ CompilerType PlatformLinux::GetSiginfoType(const llvm::Triple &triple) {
 
   CompilerType sigfault_bounds_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(sigfault_bounds_type);
   ast->AddFieldToRecordType(
       sigfault_bounds_type, "_addr_bnd",
@@ -375,7 +375,7 @@ CompilerType PlatformLinux::GetSiginfoType(const llvm::Triple &triple) {
   // siginfo_t
   CompilerType siginfo_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "__lldb_siginfo_t",
-      clang::TTK_Struct, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Struct), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(siginfo_type);
   ast->AddFieldToRecordType(siginfo_type, "si_signo", int_type,
                             lldb::eAccessPublic, 0);
@@ -400,7 +400,7 @@ CompilerType PlatformLinux::GetSiginfoType(const llvm::Triple &triple) {
   // union used to hold the signal data
   CompilerType union_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(union_type);
 
   ast->AddFieldToRecordType(
diff --git a/lldb/source/Plugins/Platform/NetBSD/PlatformNetBSD.cpp b/lldb/source/Plugins/Platform/NetBSD/PlatformNetBSD.cpp
index 393519d708d36..ce81aab557062 100644
--- a/lldb/source/Plugins/Platform/NetBSD/PlatformNetBSD.cpp
+++ b/lldb/source/Plugins/Platform/NetBSD/PlatformNetBSD.cpp
@@ -228,7 +228,7 @@ CompilerType PlatformNetBSD::GetSiginfoType(const llvm::Triple &triple) {
 
   CompilerType sigval_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "__lldb_sigval_t",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(sigval_type);
   ast->AddFieldToRecordType(sigval_type, "sival_int", int_type,
                             lldb::eAccessPublic, 0);
@@ -238,7 +238,7 @@ CompilerType PlatformNetBSD::GetSiginfoType(const llvm::Triple &triple) {
 
   CompilerType ptrace_option_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(ptrace_option_type);
   ast->AddFieldToRecordType(ptrace_option_type, "_pe_other_pid", pid_type,
                             lldb::eAccessPublic, 0);
@@ -249,13 +249,13 @@ CompilerType PlatformNetBSD::GetSiginfoType(const llvm::Triple &triple) {
   // siginfo_t
   CompilerType siginfo_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "__lldb_siginfo_t",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(siginfo_type);
 
   // struct _ksiginfo
   CompilerType ksiginfo_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "",
-      clang::TTK_Struct, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Struct), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(ksiginfo_type);
   ast->AddFieldToRecordType(ksiginfo_type, "_signo", int_type,
                             lldb::eAccessPublic, 0);
@@ -272,7 +272,7 @@ CompilerType PlatformNetBSD::GetSiginfoType(const llvm::Triple &triple) {
   // union used to hold the signal data
   CompilerType union_type = ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "",
-      clang::TTK_Union, lldb::eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeC);
   ast->StartTagDeclarationDefinition(union_type);
 
   ast->AddFieldToRecordType(
diff --git a/lldb/source/Plugins/RegisterTypeBuilder/RegisterTypeBuilderClang.cpp b/lldb/source/Plugins/RegisterTypeBuilder/RegisterTypeBuilderClang.cpp
index aeb54ef9ee24b..067768537c068 100644
--- a/lldb/source/Plugins/RegisterTypeBuilder/RegisterTypeBuilderClang.cpp
+++ b/lldb/source/Plugins/RegisterTypeBuilder/RegisterTypeBuilderClang.cpp
@@ -60,7 +60,8 @@ CompilerType RegisterTypeBuilderClang::GetRegisterType(
 
     fields_type = type_system->CreateRecordType(
         nullptr, OptionalClangModuleID(), lldb::eAccessPublic,
-        register_type_name, clang::TTK_Struct, lldb::eLanguageTypeC);
+        register_type_name, llvm::to_underlying(clang::TagTypeKind::Struct),
+        lldb::eLanguageTypeC);
     type_system->StartTagDeclarationDefinition(fields_type);
 
     // We assume that RegisterFlags has padded and sorted the fields
diff --git a/lldb/source/Plugins/SymbolFile/CTF/SymbolFileCTF.cpp b/lldb/source/Plugins/SymbolFile/CTF/SymbolFileCTF.cpp
index 62353be170cfb..7a2b4c00eedf3 100644
--- a/lldb/source/Plugins/SymbolFile/CTF/SymbolFileCTF.cpp
+++ b/lldb/source/Plugins/SymbolFile/CTF/SymbolFileCTF.cpp
@@ -320,12 +320,12 @@ static uint32_t GetBytes(uint32_t bits) { return bits / sizeof(unsigned); }
 static clang::TagTypeKind TranslateRecordKind(CTFType::Kind type) {
   switch (type) {
   case CTFType::Kind::eStruct:
-    return clang::TTK_Struct;
+    return clang::TagTypeKind::Struct;
   case CTFType::Kind::eUnion:
-    return clang::TTK_Union;
+    return clang::TagTypeKind::Union;
   default:
     lldbassert(false && "Invalid record kind!");
-    return clang::TTK_Struct;
+    return clang::TagTypeKind::Struct;
   }
 }
 
@@ -503,9 +503,9 @@ SymbolFileCTF::CreateFunction(const CTFFunction &ctf_function) {
 llvm::Expected<lldb::TypeSP>
 SymbolFileCTF::CreateRecord(const CTFRecord &ctf_record) {
   const clang::TagTypeKind tag_kind = TranslateRecordKind(ctf_record.kind);
-  CompilerType record_type =
-      m_ast->CreateRecordType(nullptr, OptionalClangModuleID(), eAccessPublic,
-                              ctf_record.name.data(), tag_kind, eLanguageTypeC);
+  CompilerType record_type = m_ast->CreateRecordType(
+      nullptr, OptionalClangModuleID(), eAccessPublic, ctf_record.name.data(),
+      llvm::to_underlying(tag_kind), eLanguageTypeC);
   m_compiler_types[record_type.GetOpaqueQualType()] = &ctf_record;
   Declaration decl;
   return MakeType(ctf_record.uid, ConstString(ctf_record.name), ctf_record.size,
@@ -562,7 +562,7 @@ llvm::Expected<lldb::TypeSP>
 SymbolFileCTF::CreateForward(const CTFForward &ctf_forward) {
   CompilerType forward_compiler_type = m_ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), eAccessPublic, ctf_forward.name,
-      clang::TTK_Struct, eLanguageTypeC);
+      llvm::to_underlying(clang::TagTypeKind::Struct), eLanguageTypeC);
   Declaration decl;
   return MakeType(ctf_forward.uid, ConstString(ctf_forward.name), 0, nullptr,
                   LLDB_INVALID_UID, Type::eEncodingIsUID, decl,
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
index 696708d3fc7cf..3174c18c97d88 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -1637,13 +1637,13 @@ DWARFASTParserClang::ParseStructureLikeDIE(const SymbolContext &sc,
   int tag_decl_kind = -1;
   AccessType default_accessibility = eAccessNone;
   if (tag == DW_TAG_structure_type) {
-    tag_decl_kind = clang::TTK_Struct;
+    tag_decl_kind = llvm::to_underlying(clang::TagTypeKind::Struct);
     default_accessibility = eAccessPublic;
   } else if (tag == DW_TAG_union_type) {
-    tag_decl_kind = clang::TTK_Union;
+    tag_decl_kind = llvm::to_underlying(clang::TagTypeKind::Union);
     default_accessibility = eAccessPublic;
   } else if (tag == DW_TAG_class_type) {
-    tag_decl_kind = clang::TTK_Class;
+    tag_decl_kind = llvm::to_underlying(clang::TagTypeKind::Class);
     default_accessibility = eAccessPrivate;
   }
 
@@ -3852,7 +3852,7 @@ void DWARFASTParserClang::ParseRustVariantPart(
       decl_context, OptionalClangModuleID(), lldb::eAccessPublic,
       std::string(
           llvm::formatv("{0}$Inner", class_clang_type.GetTypeName(false))),
-      clang::TTK_Union, lldb::eLanguageTypeRust);
+      llvm::to_underlying(clang::TagTypeKind::Union), lldb::eLanguageTypeRust);
   m_ast.StartTagDeclarationDefinition(inner_holder);
   m_ast.SetIsPacked(inner_holder);
 
@@ -3866,7 +3866,8 @@ void DWARFASTParserClang::ParseRustVariantPart(
         m_ast.GetDeclContextForType(inner_holder), OptionalClangModuleID(),
         lldb::eAccessPublic,
         std::string(llvm::formatv("{0}$Variant", member.GetName())),
-        clang::TTK_Struct, lldb::eLanguageTypeRust);
+        llvm::to_underlying(clang::TagTypeKind::Struct),
+        lldb::eLanguageTypeRust);
 
     m_ast.StartTagDeclarationDefinition(field_type);
     auto offset = member.byte_offset;
diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
index c7ff25e904abe..5b690ead1e8de 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
@@ -99,18 +99,18 @@ struct CreateMethodDecl : public TypeVisitorCallbacks {
 static clang::TagTypeKind TranslateUdtKind(const TagRecord &cr) {
   switch (cr.Kind) {
   case TypeRecordKind::Class:
-    return clang::TTK_Class;
+    return clang::TagTypeKind::Class;
   case TypeRecordKind::Struct:
-    return clang::TTK_Struct;
+    return clang::TagTypeKind::Struct;
   case TypeRecordKind::Union:
-    return clang::TTK_Union;
+    return clang::TagTypeKind::Union;
   case TypeRecordKind::Interface:
-    return clang::TTK_Interface;
+    return clang::TagTypeKind::Interface;
   case TypeRecordKind::Enum:
-    return clang::TTK_Enum;
+    return clang::TagTypeKind::Enum;
   default:
     lldbassert(false && "Invalid tag record kind!");
-    return clang::TTK_Struct;
+    return clang::TagTypeKind::Struct;
   }
 }
 
@@ -608,16 +608,17 @@ clang::QualType PdbAstBuilder::CreateRecordType(PdbTypeSymId id,
     return {};
 
   clang::TagTypeKind ttk = TranslateUdtKind(record);
-  lldb::AccessType access =
-      (ttk == clang::TTK_Class) ? lldb::eAccessPrivate : lldb::eAccessPublic;
+  lldb::AccessType access = (ttk == clang::TagTypeKind::Class)
+                                ? lldb::eAccessPrivate
+                                : lldb::eAccessPublic;
 
   ClangASTMetadata metadata;
   metadata.SetUserID(toOpaqueUid(id));
   metadata.SetIsDynamicCXXType(false);
 
-  CompilerType ct =
-      m_clang.CreateRecordType(context, OptionalClangModuleID(), access, uname,
-                               ttk, lldb::eLanguageTypeC_plus_plus, &metadata);
+  CompilerType ct = m_clang.CreateRecordType(
+      context, OptionalClangModuleID(), access, uname, llvm::to_underlying(ttk),
+      lldb::eLanguageTypeC_plus_plus, &metadata);
 
   lldbassert(ct.IsValid());
 
diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/UdtRecordCompleter.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/UdtRecordCompleter.cpp
index cf3868d077c3f..fab3ca989c0ec 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/UdtRecordCompleter.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/UdtRecordCompleter.cpp
@@ -356,14 +356,14 @@ UdtRecordCompleter::AddMember(TypeSystemClang &clang, Member *field,
   case Member::Struct:
   case Member::Union: {
     clang::TagTypeKind kind = field->kind == Member::Struct
-                                  ? clang::TagTypeKind::TTK_Struct
-                                  : clang::TagTypeKind::TTK_Union;
+                                  ? clang::TagTypeKind::Struct
+                                  : clang::TagTypeKind::Union;
     ClangASTMetadata metadata;
     metadata.SetUserID(pdb->anonymous_id);
     metadata.SetIsDynamicCXXType(false);
     CompilerType record_ct = clang.CreateRecordType(
-        parent_decl_ctx, OptionalClangModuleID(), lldb::eAccessPublic, "", kind,
-        lldb::eLanguageTypeC_plus_plus, &metadata);
+        parent_decl_ctx, OptionalClangModuleID(), lldb::eAccessPublic, "",
+        llvm::to_underlying(kind), lldb::eLanguageTypeC_plus_plus, &metadata);
     TypeSystemClang::StartTagDeclarationDefinition(record_ct);
     ClangASTImporter::LayoutInfo layout;
     clang::DeclContext *decl_ctx = clang.GetDeclContextForType(record_ct);
diff --git a/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp b/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
index 5efa5bccb85f5..e915bff9e4a47 100644
--- a/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
+++ b/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
@@ -49,13 +49,13 @@ using namespace llvm::pdb;
 static int TranslateUdtKind(PDB_UdtType pdb_kind) {
   switch (pdb_kind) {
   case PDB_UdtType::Class:
-    return clang::TTK_Class;
+    return llvm::to_underlying(clang::TagTypeKind::Class);
   case PDB_UdtType::Struct:
-    return clang::TTK_Struct;
+    return llvm::to_underlying(clang::TagTypeKind::Struct);
   case PDB_UdtType::Union:
-    return clang::TTK_Union;
+    return llvm::to_underlying(clang::TagTypeKind::Union);
   case PDB_UdtType::Interface:
-    return clang::TTK_Interface;
+    return llvm::to_underlying(clang::TagTypeKind::Interface);
   }
   llvm_unreachable("unsuported PDB UDT type");
 }
@@ -1387,9 +1387,9 @@ void PDBASTParser::AddRecordBases(
     auto is_virtual = base->isVirtualBaseClass();
 
     std::unique_ptr<clang::CXXBaseSpecifier> base_spec =
-        m_ast.CreateBaseClassSpecifier(base_comp_type.GetOpaqueQualType(),
-                                       access, is_virtual,
-                                       record_kind == clang::TTK_Class);
+        m_ast.CreateBaseClassSpecifier(
+            base_comp_type.GetOpaqueQualType(), access, is_virtual,
+            record_kind == llvm::to_underlying(clang::TagTypeKind::Class));
     lldbassert(base_spec);
 
     base_classes.push_back(std::move(base_spec));
diff --git a/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp b/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp
index f4ddc9e869148..dbceaf0ed4f44 100644
--- a/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp
+++ b/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp
@@ -420,7 +420,8 @@ void SystemRuntimeMacOSX::ReadLibdispatchTSDIndexes() {
           scratch_ts_sp->GetBuiltinTypeForEncodingAndBitSize(eEncodingUint, 16);
       CompilerType dispatch_tsd_indexes_s = scratch_ts_sp->CreateRecordType(
           nullptr, OptionalClangModuleID(), lldb::eAccessPublic,
-          "__lldb_dispatch_tsd_indexes_s", clang::TTK_Struct,
+          "__lldb_dispatch_tsd_indexes_s",
+          llvm::to_underlying(clang::TagTypeKind::Struct),
           lldb::eLanguageTypeC);
 
       TypeSystemClang::StartTagDeclarationDefinition(dispatch_tsd_indexes_s);
diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index 5f64e0e4abaf9..6f65587c4aced 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -2320,8 +2320,9 @@ CompilerType TypeSystemClang::CreateStructForIdentifier(
     return type;
   }
 
-  type = CreateRecordType(nullptr, OptionalClangModuleID(), lldb::eAccessPublic,
-                          type_name, clang::TTK_Struct, lldb::eLanguageTypeC);
+  type = CreateRecordType(
+      nullptr, OptionalClangModuleID(), lldb::eAccessPublic, type_name,
+      llvm::to_underlying(clang::TagTypeKind::Struct), lldb::eLanguageTypeC);
   StartTagDeclarationDefinition(type);
   for (const auto &field : type_fields)
     AddFieldToRecordType(type, field.first, field.second, lldb::eAccessPublic,
diff --git a/lldb/unittests/Symbol/TestTypeSystemClang.cpp b/lldb/unittests/Symbol/TestTypeSystemClang.cpp
index ec5cc776d960f..c83e6ed1d4189 100644
--- a/lldb/unittests/Symbol/TestTypeSystemClang.cpp
+++ b/lldb/unittests/Symbol/TestTypeSystemClang.cpp
@@ -295,7 +295,8 @@ TEST_F(TestTypeSystemClang, TestOwningModule) {
 
   CompilerType record_type = ast.CreateRecordType(
       nullptr, OptionalClangModuleID(200), lldb::eAccessPublic, "FooRecord",
-      clang::TTK_Struct, lldb::eLanguageTypeC_plus_plus, nullptr);
+      llvm::to_underlying(clang::TagTypeKind::Struct),
+      lldb::eLanguageTypeC_plus_plus, nullptr);
   auto *rd = TypeSystemClang::GetAsRecordDecl(record_type);
   EXPECT_FALSE(!rd);
   EXPECT_EQ(rd->getOwningModuleID(), 200u);
@@ -315,7 +316,8 @@ TEST_F(TestTypeSystemClang, TestIsClangType) {
   CompilerType bool_type(m_ast->weak_from_this(), bool_ctype);
   CompilerType record_type = m_ast->CreateRecordType(
       nullptr, OptionalClangModuleID(100), lldb::eAccessPublic, "FooRecord",
-      clang::TTK_Struct, lldb::eLanguageTypeC_plus_plus, nullptr);
+      llvm::to_underlying(clang::TagTypeKind::Struct),
+      lldb::eLanguageTypeC_plus_plus, nullptr);
   // Clang builtin type and record type should pass
   EXPECT_TRUE(ClangUtil::IsClangType(bool_type));
   EXPECT_TRUE(ClangUtil::IsClangType(record_type));
@@ -327,7 +329,8 @@ TEST_F(TestTypeSystemClang, TestIsClangType) {
 TEST_F(TestTypeSystemClang, TestRemoveFastQualifiers) {
   CompilerType record_type = m_ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "FooRecord",
-      clang::TTK_Struct, lldb::eLanguageTypeC_plus_plus, nullptr);
+      llvm::to_underlying(clang::TagTypeKind::Struct),
+      lldb::eLanguageTypeC_plus_plus, nullptr);
   QualType qt;
 
   qt = ClangUtil::GetQualType(record_type);
@@ -399,7 +402,8 @@ TEST_F(TestTypeSystemClang, TestRecordHasFields) {
   // Test that a record with no fields returns false
   CompilerType empty_base = m_ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "EmptyBase",
-      clang::TTK_Struct, lldb::eLanguageTypeC_plus_plus, nullptr);
+      llvm::to_underlying(clang::TagTypeKind::Struct),
+      lldb::eLanguageTypeC_plus_plus, nullptr);
   TypeSystemClang::StartTagDeclarationDefinition(empty_base);
   TypeSystemClang::CompleteTagDeclarationDefinition(empty_base);
 
@@ -410,7 +414,8 @@ TEST_F(TestTypeSystemClang, TestRecordHasFields) {
   // Test that a record with direct fields returns true
   CompilerType non_empty_base = m_ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "NonEmptyBase",
-      clang::TTK_Struct, lldb::eLanguageTypeC_plus_plus, nullptr);
+      llvm::to_underlying(clang::TagTypeKind::Struct),
+      lldb::eLanguageTypeC_plus_plus, nullptr);
   TypeSystemClang::StartTagDeclarationDefinition(non_empty_base);
   FieldDecl *non_empty_base_field_decl = m_ast->AddFieldToRecordType(
       non_empty_base, "MyField", int_type, eAccessPublic, 0);
@@ -426,7 +431,8 @@ TEST_F(TestTypeSystemClang, TestRecordHasFields) {
   // Test that a record with no direct fields, but fields in a base returns true
   CompilerType empty_derived = m_ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "EmptyDerived",
-      clang::TTK_Struct, lldb::eLanguageTypeC_plus_plus, nullptr);
+      llvm::to_underlying(clang::TagTypeKind::Struct),
+      lldb::eLanguageTypeC_plus_plus, nullptr);
   TypeSystemClang::StartTagDeclarationDefinition(empty_derived);
   std::unique_ptr<clang::CXXBaseSpecifier> non_empty_base_spec =
       m_ast->CreateBaseClassSpecifier(non_empty_base.GetOpaqueQualType(),
@@ -448,7 +454,8 @@ TEST_F(TestTypeSystemClang, TestRecordHasFields) {
   // returns true
   CompilerType empty_derived2 = m_ast->CreateRecordType(
       nullptr, OptionalClangModuleID(), lldb::eAccessPublic, "EmptyDerived2",
-      clang::TTK_Struct, lldb::eLanguageTypeC_plus_plus, nullptr);
+      llvm::to_underlying(clang::TagTypeKind::Struct),
+      lldb::eLanguageTypeC_plus_plus, nullptr);
   TypeSystemClang::StartTagDeclarationDefinition(empty_derived2);
   std::unique_ptr<CXXBaseSpecifier> non_empty_vbase_spec =
       m_ast->CreateBaseClassSpecifier(non_empty_base.GetOpaqueQualType(),
@@ -479,14 +486,14 @@ TEST_F(TestTypeSystemClang, TemplateArguments) {
   // template<typename T, int I> struct foo;
   ClassTemplateDecl *decl = m_ast->CreateClassTemplateDecl(
       m_ast->GetTranslationUnitDecl(), OptionalClangModuleID(), eAccessPublic,
-      "foo", TTK_Struct, infos);
+      "foo", llvm::to_underlying(clang::TagTypeKind::Struct), infos);
   ASSERT_NE(decl, nullptr);
 
   // foo<int, 47>
   ClassTemplateSpecializationDecl *spec_decl =
       m_ast->CreateClassTemplateSpecializationDecl(
           m_ast->GetTranslationUnitDecl(), OptionalClangModuleID(), decl,
-          TTK_Struct, infos);
+          llvm::to_underlying(clang::TagTypeKind::Struct), infos);
   ASSERT_NE(spec_decl, nullptr);
   CompilerType type = m_ast->CreateClassTemplateSpecializationType(spec_decl);
   ASSERT_TRUE(type);
@@ -543,7 +550,7 @@ class TestCreateClassTemplateDecl : public TestTypeSystemClang {
   CreateClassTemplate(const TypeSystemClang::TemplateParameterInfos &infos) {
     ClassTemplateDecl *decl = m_ast->CreateClassTemplateDecl(
         m_ast->GetTranslationUnitDecl(), OptionalClangModuleID(), eAccessPublic,
-        "foo", TTK_Struct, infos);
+        "foo", llvm::to_underlying(clang::TagTypeKind::Struct), infos);
     return decl;
   }