Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -3466,6 +3466,18 @@
       return false;
 
     // Fall through for conflicting redeclarations and redefinitions.
+  } else if (getLangOpts().OpenCL) {
+    QualType OldDeclaredReturnType = Old->getDeclaredReturnType();
+    QualType NewDeclaredReturnType = New->getDeclaredReturnType();
+
+    if (!Context.hasSameType(OldDeclaredReturnType, NewDeclaredReturnType) &&
+        canFullyTypeCheckRedeclaration(New, Old, NewDeclaredReturnType,
+                                       OldDeclaredReturnType)) {
+
+        Diag(New->getLocation(), diag::err_ovl_diff_return_type)
+            << New->getReturnTypeSourceRange();
+        return true;
+    }
   }
 
   // C: Function types need to be compatible, not identical. This handles