Index: clang/include/clang/Basic/LLVM.h
===================================================================
--- clang/include/clang/Basic/LLVM.h
+++ clang/include/clang/Basic/LLVM.h
@@ -22,6 +22,8 @@
 // None.h includes an enumerator that is desired & cannot be forward declared
 // without a definition of NoneType.
 #include "llvm/ADT/None.h"
+// Add this header as a workaround to unblock the XL build compiler issue.
+#include "llvm/ADT/SmallVector.h"
 
 namespace llvm {
   // ADT's.