diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 44e001ceb6dc..be2d5b38c615 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -957,8 +957,16 @@ void X86_32ABIInfo::computeInfo(CGFunctionInfo &FI) const {
   else
     State.FreeRegs = DefaultNumRegisterParameters;
 
-  if (!getCXXABI().classifyReturnType(FI))
+  if (!getCXXABI().classifyReturnType(FI)) {
     FI.getReturnInfo() = classifyReturnType(FI.getReturnType(), State);
+  } else if (FI.getReturnInfo().isIndirect()) {
+    // The C++ ABI is not aware of register usage, so we have to check if the
+    // return value was sret and put it in a register ourselves if appropriate.
+    if (State.FreeRegs) {
+      --State.FreeRegs;  // The sret parameter consumes a register.
+      FI.getReturnInfo().setInReg(true);
+    }
+  }
 
   bool UsedInAlloca = false;
   for (auto &I : FI.arguments()) {
diff --git a/clang/test/CodeGenCXX/microsoft-abi-cdecl-method-sret.cpp b/clang/test/CodeGenCXX/microsoft-abi-cdecl-method-sret.cpp
index 2f8a66ea8e87..da58c461dcc0 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-cdecl-method-sret.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-cdecl-method-sret.cpp
@@ -33,3 +33,12 @@ int main() {
 // CHECK: call void {{.*}} @"\01?variadic_sret@C@@QAA?AUS@@PBDZZ"
 // CHECK: call void @"\01?cdecl_sret@C@@QAA?AUS@@XZ"
 // CHECK: call void @"\01?byval_and_sret@C@@QAA?AUS@@U2@@Z"
+
+// __fastcall has similar issues.
+struct A {
+  S __fastcall f(int x);
+};
+S A::f(int x) {
+  return S();
+}
+// CHECK-LABEL: define x86_fastcallcc void @"\01?f@A@@QAI?AUS@@H@Z"(%struct.A* inreg %this, %struct.S* inreg noalias sret %agg.result, i32 %x)