Index: clang/lib/Sema/SemaLambda.cpp
===================================================================
--- clang/lib/Sema/SemaLambda.cpp
+++ clang/lib/Sema/SemaLambda.cpp
@@ -1272,6 +1272,34 @@
       CallOpProto.isVariadic(), /*IsCXXMethod=*/true);
   CallingConv CallOpCC = CallOpProto.getCallConv();
 
+  /// Implement emitting a version of the operator for many of the calling
+  /// conventions for MSVC, as described here:
+  /// https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623.
+  /// Experimentally, we determined that cdecl, stdcall, fastcall, and
+  /// vectorcall are generated by MSVC when it is supported by the target.
+  /// Additionally, we are ensuring that the default-free/default-member and
+  /// call-operator calling convention are generated as well.
+  /// NOTE: We intentionally generate a 'thiscall' on Win32 implicitly from the
+  /// 'member default', despite MSVC not doing so. We do this in order to ensure
+  /// that someone who intentionally places 'thiscall' on the lambda call
+  /// operator will still get that overload, since we don't have the a way of
+  /// detecting the attribute by the time we get here.
+  if (S.getLangOpts().MSVCCompat) {
+    CallingConv Convs[] = {
+        CC_C,        CC_X86StdCall, CC_X86FastCall, CC_X86VectorCall,
+        DefaultFree, DefaultMember, CallOpCC};
+    llvm::sort(Convs);
+    llvm::iterator_range<CallingConv *> Range(
+        std::begin(Convs), std::unique(std::begin(Convs), std::end(Convs)));
+    const TargetInfo &TI = S.getASTContext().getTargetInfo();
+
+    for (CallingConv C : Range) {
+      if (TI.checkCallingConvention(C) == TargetInfo::CCCR_OK)
+        F(C);
+    }
+    return;
+  }
+
   if (CallOpCC == DefaultMember && DefaultMember != DefaultFree) {
     F(DefaultFree);
     F(DefaultMember);
@@ -1475,9 +1503,6 @@
 /// C++11 [expr.prim.lambda]p6. Note that in most cases, this should emit only a
 /// single pointer conversion. In the event that the default calling convention
 /// for free and member functions is different, it will emit both conventions.
-/// FIXME: Implement emitting a version of the operator for EVERY calling
-/// convention for MSVC, as described here:
-/// https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623.
 static void addFunctionPointerConversions(Sema &S, SourceRange IntroducerRange,
                                           CXXRecordDecl *Class,
                                           CXXMethodDecl *CallOperator) {
Index: clang/test/CodeGenCXX/lambda-conversion-op-cc.cpp
===================================================================
--- clang/test/CodeGenCXX/lambda-conversion-op-cc.cpp
+++ clang/test/CodeGenCXX/lambda-conversion-op-cc.cpp
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,LIN64
 // RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-linux-gnu -DCC="__attribute__((vectorcall))" | FileCheck %s --check-prefixes=CHECK,VECCALL
-// RUN: %clang_cc1 -emit-llvm %s -o - -triple=i386-windows-pc -DWIN32 | FileCheck %s --check-prefixes=WIN32
+// RUN: %clang_cc1 -emit-llvm %s -o - -fms-compatibility -triple=i386-windows-pc -DWIN32 | FileCheck %s --check-prefixes=WIN32
 
 #ifndef CC
 #define CC
@@ -10,20 +10,31 @@
   auto lambda = [](int i, float f, double d) CC { return i + f + d; };
 
   double (*CC fp)(int, float, double) = lambda;
-  fp(0, 1.1, 2.2);
 #ifdef WIN32
   double (*__attribute__((thiscall)) fp2)(int, float, double) = lambda;
+  double (*__attribute__((stdcall)) fp3)(int, float, double) = lambda;
+  double (*__attribute__((fastcall)) fp4)(int, float, double) = lambda;
+  double (*__attribute__((vectorcall)) fp5)(int, float, double) = lambda;
+#endif // WIN32
+  fp(0, 1.1, 2.2);
+#ifdef WIN32
   fp2(0, 1.1, 2.2);
+  fp3(0, 1.1, 2.2);
+  fp4(0, 1.1, 2.2);
+  fp5(0, 1.1, 2.2);
 #endif // WIN32
 }
 
-// void usage function, calls convrsion operator.
+// void usage function, calls conversion operator.
 // LIN64: define void @_Z5usagev()
 // VECCALL: define void @_Z5usagev()
 // WIN32: define dso_local void @"?usage@@YAXXZ"()
 // CHECK: call double (i32, float, double)* @"_ZZ5usagevENK3$_0cvPFdifdEEv"
 // WIN32: call x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6A?A?<auto>@@HMN@ZXZ"
 // WIN32: call x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6E?A?<auto>@@HMN@ZXZ"
+// WIN32: call x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6G?A?<auto>@@HMN@ZXZ"
+// WIN32: call x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6I?A?<auto>@@HMN@ZXZ"
+// WIN32: call x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6Q?A?<auto>@@HMN@ZXZ"
 //
 // Conversion operator, returns __invoke.
 // CHECK: define internal double (i32, float, double)* @"_ZZ5usagevENK3$_0cvPFdifdEEv"
@@ -32,6 +43,12 @@
 // WIN32: ret double (i32, float, double)* @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CA?A?<auto>@@HMN@Z"
 // WIN32: define internal x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6E?A?<auto>@@HMN@ZXZ"
 // WIN32: ret double (i32, float, double)* @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CE?A?<auto>@@HMN@Z"
+// WIN32: define internal x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6G?A?<auto>@@HMN@ZXZ"
+// WIN32: ret double (i32, float, double)* @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CG?A?<auto>@@HMN@Z"
+// WIN32: define internal x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6I?A?<auto>@@HMN@ZXZ"
+// WIN32: ret double (i32, float, double)* @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CI?A?<auto>@@HMN@Z"
+// WIN32: define internal x86_thiscallcc double (i32, float, double)* @"??B<lambda_0>@?0??usage@@YAXXZ@QBEP6Q?A?<auto>@@HMN@ZXZ"
+// WIN32: ret double (i32, float, double)* @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CQ?A?<auto>@@HMN@Z"
 //
 // __invoke function, calls operator(). Win32 should call both.
 // LIN64: define internal double @"_ZZ5usagevEN3$_08__invokeEifd"
@@ -42,3 +59,9 @@
 // WIN32: call x86_thiscallcc double @"??R<lambda_0>@?0??usage@@YAXXZ@QBE?A?<auto>@@HMN@Z"
 // WIN32: define internal x86_thiscallcc double @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CE?A?<auto>@@HMN@Z"
 // WIN32: call x86_thiscallcc double @"??R<lambda_0>@?0??usage@@YAXXZ@QBE?A?<auto>@@HMN@Z"
+// WIN32: define internal x86_stdcallcc double @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CG?A?<auto>@@HMN@Z"
+// WIN32: call x86_thiscallcc double @"??R<lambda_0>@?0??usage@@YAXXZ@QBE?A?<auto>@@HMN@Z"
+// WIN32: define internal x86_fastcallcc double @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CI?A?<auto>@@HMN@Z"
+// WIN32: call x86_thiscallcc double @"??R<lambda_0>@?0??usage@@YAXXZ@QBE?A?<auto>@@HMN@Z"
+// WIN32: define internal x86_vectorcallcc double @"?__invoke@<lambda_0>@?0??usage@@YAXXZ@CQ?A?<auto>@@HMN@Z"
+// WIN32: call x86_thiscallcc double @"??R<lambda_0>@?0??usage@@YAXXZ@QBE?A?<auto>@@HMN@Z"