diff -ru a/clang-9.0.1.src.orig/lib/Lex/Lexer.cpp b/clang-9.0.1.src/lib/Lex/Lexer.cpp
--- a/clang-9.0.1.src.orig/lib/Lex/Lexer.cpp	2020-02-06 11:09:14.477735942 +0000
+++ b/clang-9.0.1.src/lib/Lex/Lexer.cpp	2020-02-06 11:11:57.202309851 +0000
@@ -2542,7 +2542,7 @@
         '/', '/', '/', '/',  '/', '/', '/', '/'
       };
       while (CurPtr+16 <= BufferEnd &&
-             !vec_any_eq(*(const vector unsigned char*)CurPtr, Slashes))
+             !vec_any_eq(*(const __vector unsigned char*)CurPtr, Slashes))
         CurPtr += 16;
 #else
       // Scan for '/' quickly.  Many block comments are very large.