diff --git a/llvm/include/llvm/Support/Casting.h b/llvm/include/llvm/Support/Casting.h
index 0c71882a77b1..80f09db4f7ac 100644
--- a/llvm/include/llvm/Support/Casting.h
+++ b/llvm/include/llvm/Support/Casting.h
@@ -55,8 +55,8 @@ struct isa_impl {
 /// \brief Always allow upcasts, and perform no dynamic check for them.
 template <typename To, typename From>
 struct isa_impl<To, From,
-                typename llvm::enable_if_c<
-                  llvm::is_base_of<To, From>::value
+                typename enable_if<
+                  llvm::is_base_of<To, From>
                 >::type
                > {
   static inline bool doit(const From &) { return true; }
@@ -204,12 +204,35 @@ template<class To, class FromTy> struct cast_convert_val<To,FromTy,FromTy> {
 //  cast<Instruction>(myVal)->getParent()
 //
 template <class X, class Y>
-inline typename cast_retty<X, Y>::ret_type cast(const Y &Val) {
+inline typename enable_if_c<
+  !is_same<Y, typename simplify_type<Y>::SimpleType>::value,
+  typename cast_retty<X, Y>::ret_type
+>::type cast(const Y &Val) {
   assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!");
   return cast_convert_val<X, Y,
                           typename simplify_type<Y>::SimpleType>::doit(Val);
 }
 
+template <class X, class Y>
+inline typename enable_if<
+  is_same<Y, typename simplify_type<Y>::SimpleType>,
+  typename cast_retty<X, Y>::ret_type
+>::type cast(Y &Val) {
+  assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!");
+  return cast_convert_val<X, Y,
+                          typename simplify_type<Y>::SimpleType>::doit(Val);
+}
+
+template <class X, class Y>
+inline typename enable_if<
+  is_same<Y, typename simplify_type<Y>::SimpleType>,
+  typename cast_retty<X, Y*>::ret_type
+>::type cast(Y *Val) {
+  assert(isa<X>(Val) && "cast<Ty>() argument of incompatible type!");
+  return cast_convert_val<X, Y*,
+                          typename simplify_type<Y*>::SimpleType>::doit(Val);
+}
+
 // cast_or_null<X> - Functionally identical to cast, except that a null value is
 // accepted.
 //
@@ -230,8 +253,27 @@ inline typename cast_retty<X, Y*>::ret_type cast_or_null(Y *Val) {
 //
 
 template <class X, class Y>
-inline typename cast_retty<X, Y>::ret_type dyn_cast(const Y &Val) {
-  return isa<X>(Val) ? cast<X, Y>(Val) : 0;
+inline typename enable_if_c<
+  !is_same<Y, typename simplify_type<Y>::SimpleType>::value,
+  typename cast_retty<X, Y>::ret_type
+>::type dyn_cast(const Y &Val) {
+  return isa<X>(Val) ? cast<X>(Val) : 0;
+}
+
+template <class X, class Y>
+inline typename enable_if<
+  is_same<Y, typename simplify_type<Y>::SimpleType>,
+  typename cast_retty<X, Y>::ret_type
+>::type dyn_cast(Y &Val) {
+  return isa<X>(Val) ? cast<X>(Val) : 0;
+}
+
+template <class X, class Y>
+inline typename enable_if<
+  is_same<Y, typename simplify_type<Y>::SimpleType>,
+  typename cast_retty<X, Y*>::ret_type
+>::type dyn_cast(Y *Val) {
+  return isa<X>(Val) ? cast<X>(Val) : 0;
 }
 
 // dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null