diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 6072f60..ed448cc 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -1016,6 +1016,9 @@
   if (CodeGenOpts.NoImplicitFloat)
     FuncAttrs.addAttribute(llvm::Attribute::NoImplicitFloat);
 
+  if (!CodeGenOpts.SimplifyLibCalls)
+    FuncAttrs.addAttribute("no-builtin");
+
   if (!TargetOpts.CPU.empty())
     FuncAttrs.addAttribute("target-cpu", TargetOpts.CPU);