diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h
index 6d22027..d5c433f 100644
--- a/lib/Target/X86/X86Subtarget.h
+++ b/lib/Target/X86/X86Subtarget.h
@@ -199,7 +199,8 @@
   }
 
   bool isTargetWin64() const {
-    return In64BitMode && (isTargetMingw() || isTargetWindows());
+    // FIXME: x86_64-cygwin has not been released yet.
+    return In64BitMode && (isTargetCygMing() || isTargetWindows());
   }
 
   bool isTargetEnvMacho() const {