diff --git a/llvm/lib/Demangle/MicrosoftDemangle.cpp b/llvm/lib/Demangle/MicrosoftDemangle.cpp
index a98d9fe45fe18..303207176be71 100644
--- a/llvm/lib/Demangle/MicrosoftDemangle.cpp
+++ b/llvm/lib/Demangle/MicrosoftDemangle.cpp
@@ -1713,7 +1713,7 @@ CallingConv Demangler::demangleCallingConvention(StringView &MangledName) {
     return CallingConv::Vectorcall;
   case 'S':
     return CallingConv::Swift;
-  case 'T':
+  case 'W':
     return CallingConv::SwiftAsync;
   }
 
diff --git a/llvm/test/Demangle/ms-mangle.test b/llvm/test/Demangle/ms-mangle.test
index 6995d70196665..0eee2be9097fa 100644
--- a/llvm/test/Demangle/ms-mangle.test
+++ b/llvm/test/Demangle/ms-mangle.test
@@ -341,7 +341,7 @@
 ?swift_func@@YSXXZ
 ; CHECK: void __attribute__((__swiftcall__)) swift_func(void)
 
-?swift_async_func@@YTXXZ
+?swift_async_func@@YWXXZ
 ; CHECK: void __attribute__((__swiftasynccall__)) swift_async_func(void)
 
 ??$fn_tmpl@$1?extern_c_func@@YAXXZ@@YAXXZ