diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 1d81e82..3bf6779 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -806,6 +806,8 @@
   Opts.NoCommon = Args.hasArg(OPT_fno_common);
   Opts.NoImplicitFloat = Args.hasArg(OPT_no_implicit_float);
   Opts.OptimizeSize = Args.hasArg(OPT_Os);
+  Opts.SimplifyLibCalls = !(Args.hasArg(OPT_fno_builtin) ||
+                            Args.hasArg(OPT_ffreestanding));
   Opts.UnrollLoops = (Opts.OptimizationLevel > 1 && !Opts.OptimizeSize);
 
   Opts.AsmVerbose = Args.hasArg(OPT_masm_verbose);