Index: clang/include/clang/Basic/TargetInfo.h
===================================================================
--- clang/include/clang/Basic/TargetInfo.h
+++ clang/include/clang/Basic/TargetInfo.h
@@ -1092,6 +1092,13 @@
   /// either; the entire thing is pretty badly mangled.
   virtual bool hasProtectedVisibility() const { return true; }
 
+  /// Does this target aim for source level compatibility with
+  /// Microsoft C++ code using dllimport/export attributes?
+  virtual bool shouldDLLImportComdatSymbols() const {
+    return getTriple().isWindowsMSVCEnvironment() ||
+           getTriple().isWindowsItaniumEnvironment() || getTriple().isPS4CPU();
+  }
+
   /// An optional hook that targets can implement to perform semantic
   /// checking on attribute((section("foo"))) specifiers.
   ///
Index: clang/lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3198,7 +3198,7 @@
       return false;
 
     if (CGM.getVTables().isVTableExternal(RD))
-      return IsDLLImport && !CGM.getTriple().isWindowsItaniumEnvironment()
+      return IsDLLImport && !CGM.getTarget().shouldDLLImportComdatSymbols()
                  ? false
                  : true;
 
@@ -3455,7 +3455,7 @@
       const CXXRecordDecl *RD = cast<CXXRecordDecl>(Record->getDecl());
       if (RD->hasAttr<WeakAttr>())
         return llvm::GlobalValue::WeakODRLinkage;
-      if (CGM.getTriple().isWindowsItaniumEnvironment())
+      if (CGM.getTarget().shouldDLLImportComdatSymbols())
         if (RD->hasAttr<DLLImportAttr>() &&
             ShouldUseExternalRTTIDescriptor(CGM, Ty))
           return llvm::GlobalValue::ExternalLinkage;
@@ -3513,7 +3513,7 @@
 
   llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass =
       llvm::GlobalValue::DefaultStorageClass;
-  if (CGM.getTriple().isWindowsItaniumEnvironment()) {
+  if (CGM.getTarget().shouldDLLImportComdatSymbols()) {
     auto RD = Ty->getAsCXXRecordDecl();
     if (RD && RD->hasAttr<DLLExportAttr>())
       DLLStorageClass = llvm::GlobalValue::DLLExportStorageClass;
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -6775,16 +6775,14 @@
 
 static void handleDLLAttr(Sema &S, Decl *D, const ParsedAttr &A) {
   if (isa<ClassTemplatePartialSpecializationDecl>(D) &&
-      (S.Context.getTargetInfo().getCXXABI().isMicrosoft() ||
-       S.Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment())) {
+      (S.Context.getTargetInfo().shouldDLLImportComdatSymbols())) {
     S.Diag(A.getRange().getBegin(), diag::warn_attribute_ignored) << A;
     return;
   }
 
   if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isInlined() && A.getKind() == ParsedAttr::AT_DLLImport &&
-        !(S.Context.getTargetInfo().getCXXABI().isMicrosoft() ||
-          S.Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment())) {
+        !(S.Context.getTargetInfo().shouldDLLImportComdatSymbols())) {
       // MinGW doesn't allow dllimport on inline functions.
       S.Diag(A.getRange().getBegin(), diag::warn_attribute_ignored_on_inline)
           << A;
@@ -6793,8 +6791,7 @@
   }
 
   if (const auto *MD = dyn_cast<CXXMethodDecl>(D)) {
-    if ((S.Context.getTargetInfo().getCXXABI().isMicrosoft() ||
-         S.Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment()) &&
+    if ((S.Context.getTargetInfo().shouldDLLImportComdatSymbols()) &&
         MD->getParent()->isLambda()) {
       S.Diag(A.getRange().getBegin(), diag::err_attribute_dll_lambda) << A;
       return;
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -6071,8 +6071,8 @@
   Attr *ClassAttr = getDLLAttr(Class);
 
   // MSVC inherits DLL attributes to partial class template specializations.
-  if ((Context.getTargetInfo().getCXXABI().isMicrosoft() || 
-       Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment()) && !ClassAttr) {
+  if (Context.getTargetInfo().getTarget().shouldDLLImportComdatSymbols() &&
+      !ClassAttr) {
     if (auto *Spec = dyn_cast<ClassTemplatePartialSpecializationDecl>(Class)) {
       if (Attr *TemplateAttr =
               getDLLAttr(Spec->getSpecializedTemplate()->getTemplatedDecl())) {
@@ -6092,8 +6092,7 @@
     return;
   }
 
-  if ((Context.getTargetInfo().getCXXABI().isMicrosoft() || 
-       Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment()) &&
+  if (Context.getTargetInfo().shouldDLLImportComdatSymbols() &&
       !ClassAttr->isInherited()) {
     // Diagnose dll attributes on members of class with dll attribute.
     for (Decl *Member : Class->decls()) {
@@ -6158,8 +6157,7 @@
       if (MD->isInlined()) {
         // MinGW does not import or export inline methods. But do it for
         // template instantiations.
-        if (!Context.getTargetInfo().getCXXABI().isMicrosoft() &&
-            !Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment() &&
+        if (!Context.getTargetInfo().shouldDLLImportComdatSymbols() &&
             TSK != TSK_ExplicitInstantiationDeclaration &&
             TSK != TSK_ExplicitInstantiationDefinition)
           continue;
Index: clang/lib/Sema/SemaTemplate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplate.cpp
+++ clang/lib/Sema/SemaTemplate.cpp
@@ -9759,8 +9759,7 @@
       Def->setTemplateSpecializationKind(TSK);
 
       if (!getDLLAttr(Def) && getDLLAttr(Specialization) &&
-          (Context.getTargetInfo().getCXXABI().isMicrosoft() ||
-           Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment())) {
+          Context.getTargetInfo().shouldDLLImportComdatSymbols()) {
         // In the MS ABI, an explicit instantiation definition can add a dll
         // attribute to a template with a previous instantiation declaration.
         // MinGW doesn't allow this.
@@ -9777,8 +9776,7 @@
     bool NewlyDLLExported =
         !PreviouslyDLLExported && Specialization->hasAttr<DLLExportAttr>();
     if (Old_TSK == TSK_ImplicitInstantiation && NewlyDLLExported &&
-        (Context.getTargetInfo().getCXXABI().isMicrosoft() ||
-         Context.getTargetInfo().getTriple().isWindowsItaniumEnvironment())) {
+        Context.getTargetInfo().shouldDLLImportComdatSymbols()) {
       // In the MS ABI, an explicit instantiation definition can add a dll
       // attribute to a template with a previous implicit instantiation.
       // MinGW doesn't allow this. We limit clang to only adding dllexport, to