Some compilers do require Diagnostic.h to be present here.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149785 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Frontend/Utils.h b/include/clang/Frontend/Utils.h
index 26cda55..7961be4 100644
--- a/include/clang/Frontend/Utils.h
+++ b/include/clang/Frontend/Utils.h
@@ -14,7 +14,7 @@
 #ifndef LLVM_CLANG_FRONTEND_UTILS_H
 #define LLVM_CLANG_FRONTEND_UTILS_H
 
-#include "clang/Basic/LLVM.h"
+#include "clang/Basic/Diagnostic.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/StringRef.h"