fix a typo, patch by PaX team.

llvm-svn: 129141
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 4ebdd8c..9e0eab3 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -1093,7 +1093,7 @@
   }
   if (!Args.hasFlag(options::OPT_fmerge_all_constants,
                     options::OPT_fno_merge_all_constants))
-    CmdArgs.push_back("-no-merge-all-constants");
+    CmdArgs.push_back("-fno-merge-all-constants");
 
   // LLVM Code Generator Options.