Index: lib/Target/X86/X86AsmPrinter.cpp
===================================================================
--- lib/Target/X86/X86AsmPrinter.cpp
+++ lib/Target/X86/X86AsmPrinter.cpp
@@ -535,6 +535,12 @@
     }
   }
   OutStreamer->EmitSyntaxDirective();
+
+  // If this is not inline asm and we're in 16-bit
+  // mode prefix assembly with .code16.
+  bool is16 = TT.getEnvironment() == Triple::CODE16;
+  if (M.getModuleInlineAsm().empty() && is16)
+    OutStreamer->EmitAssemblerFlag(MCAF_Code16);
 }
 
 static void
Index: test/CodeGen/X86/x86-16.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/x86-16.ll
@@ -0,0 +1,20 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
+target triple = "i386-unknown-linux-code16"
+
+; Function Attrs: nounwind
+define i32 @main() #0 {
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  ret i32 0
+}
+
+; CHECK: .code16
+; CHECK-LABEL: main
+
+
+attributes #0 = { nounwind }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 3.9.0 (trunk 265439) (llvm/trunk 265567)"}
\ No newline at end of file