Index: lib/AST/ASTImporter.cpp
===================================================================
--- lib/AST/ASTImporter.cpp
+++ lib/AST/ASTImporter.cpp
@@ -4298,9 +4298,13 @@
 
     D2->setTemplateSpecializationKind(D->getTemplateSpecializationKind());
 
-    // Add the specialization to this context.
+    // Set the context of this specialization/instantiation.
     D2->setLexicalDeclContext(LexicalDC);
-    LexicalDC->addDeclInternal(D2);
+
+    // Add to the DC only if it was an explicit specialization/instantiation.
+    if (D2->isExplicitInstantiationOrSpecialization()) {
+      LexicalDC->addDeclInternal(D2);
+    }
   }
   Importer.Imported(D, D2);
   if (D->isCompleteDefinition() && ImportDefinition(D, D2))
Index: unittests/AST/ASTImporterTest.cpp
===================================================================
--- unittests/AST/ASTImporterTest.cpp
+++ unittests/AST/ASTImporterTest.cpp
@@ -1246,7 +1246,7 @@
 
 TEST_P(
     ASTImporterTestBase,
-    DISABLED_TUshouldNotContainClassTemplateSpecializationOfImplicitInstantiation) {
+    TUshouldNotContainClassTemplateSpecializationOfImplicitInstantiation) {
 
   Decl *From, *To;
   std::tie(From, To) = getImportedDecl(