diff --git a/clang/lib/ASTMatchers/Dynamic/Marshallers.h b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
--- a/clang/lib/ASTMatchers/Dynamic/Marshallers.h
+++ b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
@@ -27,6 +27,7 @@
 #include "clang/Basic/AttrKinds.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/OpenMPKinds.h"
+#include "clang/Basic/TypeTraits.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
@@ -214,6 +215,35 @@
   static llvm::Optional<std::string> getBestGuess(const VariantValue &Value);
 };
 
+template <> struct ArgTypeTraits<UnaryExprOrTypeTrait> {
+private:
+  static Optional<UnaryExprOrTypeTrait>
+  getUnaryOrTypeTraitKind(llvm::StringRef ClauseKind) {
+    // FIXME: Type traits should probably be in a `.def` to make less error
+    // prone.
+    return llvm::StringSwitch<Optional<UnaryExprOrTypeTrait>>(ClauseKind)
+        .Case("UETT_SizeOf", UETT_SizeOf)
+        .Case("UETT_AlignOf", UETT_AlignOf)
+        .Case("UETT_VecStep", UETT_VecStep)
+        .Case("UETT_OpenMPRequiredSimdAlign", UETT_OpenMPRequiredSimdAlign)
+        .Case("UETT_PreferredAlignOf", UETT_PreferredAlignOf)
+        .Default(llvm::None);
+  }
+
+public:
+  static bool is(const VariantValue &Value) {
+    return Value.isString() && getUnaryOrTypeTraitKind(Value.getString());
+  }
+
+  static UnaryExprOrTypeTrait get(const VariantValue &Value) {
+    return *getUnaryOrTypeTraitKind(Value.getString());
+  }
+
+  static ArgKind getKind() { return ArgKind(ArgKind::AK_String); }
+
+  static llvm::Optional<std::string> getBestGuess(const VariantValue &Value);
+};
+
 /// Matcher descriptor interface.
 ///
 /// Provides a \c create() method that constructs the matcher from the provided
diff --git a/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp b/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp
--- a/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Marshallers.cpp
@@ -95,3 +95,17 @@
                           "OMPC_");
   return llvm::None;
 }
+
+llvm::Optional<std::string>
+clang::ast_matchers::dynamic::internal::ArgTypeTraits<
+    clang::UnaryExprOrTypeTrait>::getBestGuess(const VariantValue &Value) {
+  static constexpr llvm::StringRef Allowed[] = {
+      "UETT_SizeOf",           "UETT_AlignOf",
+      "UETT_VecStep",          "UETT_OpenMPRequiredSimdAlign",
+      "UETT_PreferredAlignOf",
+  };
+  if (Value.isString())
+    return ::getBestGuess(Value.getString(), llvm::makeArrayRef(Allowed),
+                          "UETT_");
+  return llvm::None;
+}
diff --git a/clang/lib/ASTMatchers/Dynamic/Registry.cpp b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
--- a/clang/lib/ASTMatchers/Dynamic/Registry.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
@@ -95,9 +95,6 @@
 RegistryMaps::RegistryMaps() {
   // TODO: Here is the list of the missing matchers, grouped by reason.
   //
-  // Need Variant/Parser fixes:
-  // ofKind
-  //
   // Polymorphic + argument overload:
   // findAll
   //
@@ -458,6 +455,7 @@
   REGISTER_MATCHER(objcThrowStmt);
   REGISTER_MATCHER(objcTryStmt);
   REGISTER_MATCHER(ofClass);
+  REGISTER_MATCHER(ofKind);
   REGISTER_MATCHER(ompDefaultClause);
   REGISTER_MATCHER(ompExecutableDirective);
   REGISTER_MATCHER(on);
diff --git a/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp b/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp
--- a/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp
+++ b/clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp
@@ -242,6 +242,14 @@
   EXPECT_TRUE(matches("void f(int a, int x);", M));
   EXPECT_FALSE(matches("void f(int x, int a);", M));
 
+  Code = "unaryExprOrTypeTraitExpr(ofKind(\"UETT_SizeOf\"))";
+  llvm::Optional<DynTypedMatcher> UnaryExprSizeOf(
+      Parser::parseMatcherExpression(Code, nullptr, nullptr, &Error));
+  EXPECT_EQ("", Error.toStringFull());
+  Matcher<Stmt> MStmt = UnaryExprSizeOf->unconditionalConvertTo<Stmt>();
+  EXPECT_TRUE(matches("unsigned X = sizeof(int);", MStmt));
+  EXPECT_FALSE(matches("unsigned X = alignof(int);", MStmt));
+
   Code = "hasInitializer(\n    binaryOperator(hasLHS(\"A\")))";
   EXPECT_TRUE(!Parser::parseMatcherExpression(Code, &Error).hasValue());
   EXPECT_EQ("1:1: Error parsing argument 1 for matcher hasInitializer.\n"