diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -3395,7 +3395,7 @@
      return SemaBuiltinConstantArgRange(TheCall, 3, 0, 7);
   case PPC::BI__builtin_ppc_tw:
   case PPC::BI__builtin_ppc_tdw:
-    return SemaBuiltinConstantArgRange(TheCall, 2, 0, 31);
+    return SemaBuiltinConstantArgRange(TheCall, 2, 1, 31);
   case PPC::BI__builtin_ppc_cmpeqb:
   case PPC::BI__builtin_ppc_setb:
   case PPC::BI__builtin_ppc_maddhd: