diff --git a/llvm/include/llvm/Support/Casting.h b/llvm/include/llvm/Support/Casting.h
--- a/llvm/include/llvm/Support/Casting.h
+++ b/llvm/include/llvm/Support/Casting.h
@@ -525,6 +525,13 @@
   }
 };
 
+template <typename T> struct CastInfo<T, T> {
+  static bool isPossible(const T &t) { return true; }
+  static decltype(auto) doCast(const T &t) { return t; }
+  static decltype(auto) castFailed() { return T(nullptr); }
+  static decltype(auto) doCastIfPossible(const T &t) { return t; }
+};
+
 //===----------------------------------------------------------------------===//
 // Pre-specialized CastInfo
 //===----------------------------------------------------------------------===//