diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 3eb74ca59525..c2ed7e6506e5 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -300,6 +300,7 @@ def fno_exceptions : Flag<"-fno-exceptions">, Group<f_Group>;
 def fno_inline_functions : Flag<"-fno-inline-functions">, Group<clang_ignored_f_Group>;
 def fno_inline : Flag<"-fno-inline">, Group<clang_ignored_f_Group>;
 def fno_keep_inline_functions : Flag<"-fno-keep-inline-functions">, Group<clang_ignored_f_Group>;
+def fno_lax_vector_conversions : Flag<"-fno-lax-vector-conversions">, Group<f_Group>;
 def fno_math_errno : Flag<"-fno-math-errno">, Group<f_Group>;
 def fno_merge_all_constants : Flag<"-fno-merge-all-constants">, Group<f_Group>;
 def fno_ms_extensions : Flag<"-fno-ms-extensions">, Group<f_Group>;
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index bc521008cf7c..28a6a6900a23 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -1034,7 +1034,12 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   Args.AddLastArg(CmdArgs, options::OPT_femit_all_decls);
   Args.AddLastArg(CmdArgs, options::OPT_ffreestanding);
   Args.AddLastArg(CmdArgs, options::OPT_fheinous_gnu_extensions);
-  Args.AddLastArg(CmdArgs, options::OPT_flax_vector_conversions);
+
+  // -flax-vector-conversions is default.
+  if (!Args.hasFlag(options::OPT_flax_vector_conversions,
+                    options::OPT_fno_lax_vector_conversions))
+    CmdArgs.push_back("-fno-lax-vector-conversions");
+
   Args.AddLastArg(CmdArgs, options::OPT_fno_caret_diagnostics);
   Args.AddLastArg(CmdArgs, options::OPT_fno_show_column);
   Args.AddLastArg(CmdArgs, options::OPT_fobjc_gc_only);