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
@@ -170,7 +170,7 @@
 private:
   static Optional<CastKind> getCastKind(llvm::StringRef AttrKind) {
     return llvm::StringSwitch<Optional<CastKind>>(AttrKind)
-#define CAST_OPERATION(Name) .Case( #Name, CK_##Name)
+#define CAST_OPERATION(Name) .Case("CK_" #Name, CK_##Name)
 #include "clang/AST/OperationKinds.def"
         .Default(llvm::None);
   }
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
@@ -67,11 +67,12 @@
 clang::ast_matchers::dynamic::internal::ArgTypeTraits<
     clang::CastKind>::getBestGuess(const VariantValue &Value) {
   static constexpr llvm::StringRef Allowed[] = {
-#define CAST_OPERATION(Name) #Name,
+#define CAST_OPERATION(Name) "CK_" #Name,
 #include "clang/AST/OperationKinds.def"
   };
   if (Value.isString())
-    return ::getBestGuess(Value.getString(), llvm::makeArrayRef(Allowed));
+    return ::getBestGuess(Value.getString(), llvm::makeArrayRef(Allowed),
+                          "CK_");
   return llvm::None;
 }