Index: include/clang/Sema/DeclSpec.h
===================================================================
--- include/clang/Sema/DeclSpec.h
+++ include/clang/Sema/DeclSpec.h
@@ -2208,6 +2208,9 @@
   /// redeclaration time if the decl is static.
   bool isStaticMember();
 
+  /// Returns true if this declares a constructor or a destructor.
+  bool isCtorOrDtor();
+
   void setRedeclaration(bool Val) { Redeclaration = Val; }
   bool isRedeclaration() const { return Redeclaration; }
 };
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -2915,7 +2915,7 @@
   /// Adjust the calling convention of a method to be the ABI default if it
   /// wasn't specified explicitly.  This handles method types formed from
   /// function type typedefs and typename template arguments.
-  void adjustMemberFunctionCC(QualType &T, bool IsStatic);
+  void adjustMemberFunctionCC(QualType &T, bool IsStatic, bool IsCtorOrDtor);
 
   // Check if there is an explicit attribute, but only look through parens.
   // The intent is to look for an attribute on the current declarator, but not
Index: lib/Sema/DeclSpec.cpp
===================================================================
--- lib/Sema/DeclSpec.cpp
+++ lib/Sema/DeclSpec.cpp
@@ -351,6 +351,11 @@
               getName().OperatorFunctionId.Operator));
 }
 
+bool Declarator::isCtorOrDtor() {
+  return (getName().getKind() == UnqualifiedId::IK_ConstructorName) ||
+         (getName().getKind() == UnqualifiedId::IK_DestructorName);
+}
+
 bool DeclSpec::hasTagDefinition() const {
   if (!TypeSpecOwned)
     return false;
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -7219,7 +7219,7 @@
       << DeclSpec::getSpecifierName(TSCS);
 
   if (D.isFirstDeclarationOfMember())
-    adjustMemberFunctionCC(R, D.isStaticMember());
+    adjustMemberFunctionCC( R, D.isStaticMember(), D.isCtorOrDtor());
 
   bool isFriend = false;
   FunctionTemplateDecl *FunctionTemplate = nullptr;
Index: lib/Sema/SemaType.cpp
===================================================================
--- lib/Sema/SemaType.cpp
+++ lib/Sema/SemaType.cpp
@@ -2269,8 +2269,11 @@
 
   // Adjust the default free function calling convention to the default method
   // calling convention.
+  bool is_ctor_or_dtor =
+      (Entity.getNameKind() == DeclarationName::CXXConstructorName) ||
+      (Entity.getNameKind() == DeclarationName::CXXDestructorName);
   if (T->isFunctionType())
-    adjustMemberFunctionCC(T, /*IsStatic=*/false);
+    adjustMemberFunctionCC(T, /*IsStatic=*/false, is_ctor_or_dtor);
 
   return Context.getMemberPointerType(T, Class.getTypePtr());
 }
@@ -5842,24 +5845,35 @@
   return false;
 }
 
-void Sema::adjustMemberFunctionCC(QualType &T, bool IsStatic) {
+void Sema::adjustMemberFunctionCC(QualType &T, bool IsStatic,
+                                  bool IsCtorOrDtor) {
   FunctionTypeUnwrapper Unwrapped(*this, T);
   const FunctionType *FT = Unwrapped.get();
   bool IsVariadic = (isa<FunctionProtoType>(FT) &&
                      cast<FunctionProtoType>(FT)->isVariadic());
-
-  // Only adjust types with the default convention.  For example, on Windows we
-  // should adjust a __cdecl type to __thiscall for instance methods, and a
-  // __thiscall type to __cdecl for static methods.
   CallingConv CurCC = FT->getCallConv();
-  CallingConv FromCC =
-      Context.getDefaultCallingConvention(IsVariadic, IsStatic);
-  CallingConv ToCC = Context.getDefaultCallingConvention(IsVariadic, !IsStatic);
-  if (CurCC != FromCC || FromCC == ToCC)
-    return;
+  CallingConv ToCC;
 
-  if (hasExplicitCallingConv(T))
-    return;
+  // MS compiler transforms __stdcall in ctors/dtors to __thiscall in 32 bit
+  // mode. We should do the same.
+  if ((CurCC == CC_X86StdCall) && IsCtorOrDtor &&
+      (Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&
+       Context.getTargetInfo().getTriple().isArch32Bit()))
+    ToCC = CC_X86ThisCall;
+  // Default adjustment.
+  else {
+    // Only adjust types with the default convention.  For example, on Windows
+    // we should adjust a __cdecl type to __thiscall for instance methods, and a
+    // __thiscall type to __cdecl for static methods.
+    CallingConv FromCC =
+        Context.getDefaultCallingConvention(IsVariadic, IsStatic);
+    ToCC = Context.getDefaultCallingConvention(IsVariadic, !IsStatic);
+    if (CurCC != FromCC || FromCC == ToCC)
+      return;
+
+    if (hasExplicitCallingConv(T))
+      return;
+  }
 
   FT = Context.adjustFunctionType(FT, FT->getExtInfo().withCallingConv(ToCC));
   QualType Wrapped = Unwrapped.wrap(*this, FT);
Index: test/CodeGenCXX/microsoft-abi-structors.cpp
===================================================================
--- test/CodeGenCXX/microsoft-abi-structors.cpp
+++ test/CodeGenCXX/microsoft-abi-structors.cpp
@@ -5,6 +5,7 @@
 // RUN: FileCheck --check-prefix DTORS %s < %t
 // RUN: FileCheck --check-prefix DTORS2 %s < %t
 // RUN: FileCheck --check-prefix DTORS3 %s < %t
+// RUN: FileCheck --check-prefix DTORS4 %s < %t
 //
 // RUN: %clang_cc1 -emit-llvm %s -o - -mconstructor-aliases -triple=x86_64-pc-win32 -fno-rtti | FileCheck --check-prefix DTORS-X64 %s
 
@@ -458,3 +459,18 @@
 // CHECK:               (%"struct.(anonymous namespace)::A"* %this, i32 %should_call_delete)
 // CHECK: define internal x86_thiscallcc void @"\01??1A@?A@@UAE@XZ"
 // CHECK:               (%"struct.(anonymous namespace)::A"* %this)
+
+// Check that we correctly transform __stdcall to __thiscall for ctors and
+// dtors.
+class G {
+ public:
+  __stdcall G() {};
+// DTORS4: define linkonce_odr x86_thiscallcc %class.G* @"\01??0G@@QAE@XZ"
+  __stdcall ~G() {};
+// DTORS4: define linkonce_odr x86_thiscallcc void @"\01??1G@@QAE@XZ"
+};
+
+extern void testG() {
+  G g;
+}
+