Index: lib/CodeGen/CGCXX.cpp
===================================================================
--- lib/CodeGen/CGCXX.cpp
+++ lib/CodeGen/CGCXX.cpp
@@ -136,7 +136,12 @@
 
   // available_externally definitions aren't real definitions, so we cannot
   // create an alias to one.
-  if (TargetLinkage == llvm::GlobalValue::AvailableExternallyLinkage)
+  // Declarations with dllimport attribute have their linkage set to
+  // availableExternallyLinkage. In the MS ABI these represent real
+  // definitions, so an alias can be created.
+  if (TargetLinkage == llvm::GlobalValue::AvailableExternallyLinkage &&
+      !Context.getTargetInfo().getCXXABI().isMicrosoft() &&
+      !AliasDecl.getDecl()->hasAttr<DLLImportAttr>())
     return true;
 
   // Check if we have it already.
Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -3801,8 +3801,9 @@
 static void emitCXXDestructor(CodeGenModule &CGM, const CXXDestructorDecl *dtor,
                               StructorType dtorType) {
   // The complete destructor is equivalent to the base destructor for
-  // classes with no virtual bases, so try to emit it as an alias.
-  if (!dtor->getParent()->getNumVBases() &&
+  // classes with no virtual bases, or classes that have dllimport attribute,
+  // so try to emit it as an alias.
+  if ((!dtor->getParent()->getNumVBases() || dtor->hasAttr<DLLImportAttr>()) &&
       (dtorType == StructorType::Complete || dtorType == StructorType::Base)) {
     bool ProducedAlias = !CGM.TryEmitDefinitionAsAlias(
         GlobalDecl(dtor, Dtor_Complete), GlobalDecl(dtor, Dtor_Base), true);
Index: test/CodeGenCXX/dllimport-base.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/dllimport-base.cpp
@@ -0,0 +1,52 @@
+// RUN: %clang_cc1 -triple i386-pc-windows -emit-llvm -fms-compatibility %s -x c++ -o - | FileCheck %s
+
+// CHECK: declare dllimport x86_thiscallcc void @"\01??1VirtualClass@test1@@UAE@XZ"
+// CHECK: declare dllimport x86_thiscallcc void @"\01??1VirtualClass@test2@@UAE@XZ"
+// CHECK:  declare dllimport x86_thiscallcc void @"\01??1VirtualClass@test3@@UAE@XZ"
+// CHECK-NOT: ??_DVirtualClass@@QEAAXXZ
+
+namespace test1 {
+struct __declspec(dllimport) VirtualClass {
+public:
+  virtual ~VirtualClass(){};
+};
+
+int main() {
+  VirtualClass c;
+  return 0;
+}
+} // namespace test1
+
+namespace test2 {
+class BaseClass {
+public:
+  virtual ~BaseClass(){};
+};
+
+class __declspec(dllimport) VirtualClass : public BaseClass {
+public:
+  virtual ~VirtualClass(){};
+};
+
+int main() {
+  VirtualClass c;
+  return 0;
+}
+} // namespace test2
+
+namespace test3 {
+class BaseClass {
+public:
+  virtual ~BaseClass(){};
+};
+
+class __declspec(dllimport) VirtualClass : public virtual BaseClass {
+public:
+  virtual ~VirtualClass(){};
+};
+
+int main() {
+  VirtualClass c;
+  return 0;
+}
+} // namespace test3