diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp
@@ -163,5 +163,7 @@
 
   TextAlignFillValue = 0x90;
 
+  AllowAtInName = true;
+
   UseIntegratedAssembler = true;
 }
diff --git a/llvm/test/MC/X86/stdcall.s b/llvm/test/MC/X86/stdcall.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/X86/stdcall.s
@@ -0,0 +1,19 @@
+# RUN: llvm-mc %s -filetype=obj -o - -triple i686-windows-msvc | llvm-nm - | FileCheck %s
+# RUN: llvm-mc %s -filetype=obj -o - -triple i686-windows-gnu | llvm-nm - | FileCheck %s
+
+# CHECK: T _mystdcall@8{{$}}
+# CHECK: T foo
+
+.text
+.global _mystdcall@8
+_mystdcall@8:
+	movl 4(%esp), %eax
+	addl 8(%esp), %eax
+	retl $8
+
+.global foo
+foo:
+	pushl $1
+	pushl $2
+	calll _mystdcall@8
+	retl