diff --git a/mlir/include/mlir/Support/LLVM.h b/mlir/include/mlir/Support/LLVM.h
--- a/mlir/include/mlir/Support/LLVM.h
+++ b/mlir/include/mlir/Support/LLVM.h
@@ -23,6 +23,13 @@
 #include "llvm/ADT/None.h"
 #include "llvm/Support/Casting.h"
 
+// Workaround for clang-5 (PR41549)
+#if defined(__clang_major__)
+#if __clang_major__ <= 5
+#include "llvm/ADT/SmallVector.h"
+#endif
+#endif
+
 // Forward declarations.
 namespace llvm {
 // String types