Index: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaDeclCXX.cpp
+++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp
@@ -4804,6 +4804,9 @@
       }
     }
 
+    if (!cast<NamedDecl>(Member)->isExternallyVisible())
+      continue;
+
     if (!getDLLAttr(Member)) {
       auto *NewAttr =
           cast<InheritableAttr>(ClassAttr->clone(S.getASTContext()));
Index: cfe/trunk/test/CodeGenCXX/dllexport.cpp
===================================================================
--- cfe/trunk/test/CodeGenCXX/dllexport.cpp
+++ cfe/trunk/test/CodeGenCXX/dllexport.cpp
@@ -691,6 +691,15 @@
 USEMEMFUNC(ExplicitInstantiationDeclExportedTemplate<int>, f);
 // M32-DAG: {{declare|define available_externally}} x86_thiscallcc void @"\01?f@?$ExplicitInstantiationDeclExportedTemplate@H@@QAEXXZ"
 
+namespace { struct InternalLinkageType {}; }
+struct __declspec(dllexport) PR23308 {
+  void f(InternalLinkageType*);
+};
+void PR23308::f(InternalLinkageType*) {}
+long use(PR23308* p) { p->f(nullptr); }
+// M32-DAG: define internal x86_thiscallcc void @"\01?f@PR23308@@QAEXPAUInternalLinkageType@?A@@@Z"
+
+
 
 //===----------------------------------------------------------------------===//
 // Classes with template base classes
Index: cfe/trunk/test/SemaCXX/dllexport.cpp
===================================================================
--- cfe/trunk/test/SemaCXX/dllexport.cpp
+++ cfe/trunk/test/SemaCXX/dllexport.cpp
@@ -393,6 +393,12 @@
 template <typename T> struct __declspec(dllexport) ExplicitInstantiationDeclExportedTemplate {}; // expected-note{{attribute is here}}
 extern template struct ExplicitInstantiationDeclExportedTemplate<int>; // expected-warning{{explicit instantiation declaration should not be 'dllexport'}}
 
+namespace { struct InternalLinkageType {}; }
+struct __declspec(dllexport) PR23308 {
+  void f(InternalLinkageType*);
+};
+void PR23308::f(InternalLinkageType*) {} // No error; we don't try to export f because it has internal linkage.
+
 //===----------------------------------------------------------------------===//
 // Classes with template base classes
 //===----------------------------------------------------------------------===//