Index: lib/AST/ASTImporter.cpp
===================================================================
--- lib/AST/ASTImporter.cpp
+++ lib/AST/ASTImporter.cpp
@@ -1959,7 +1959,7 @@
   // but this particular declaration is not that definition, import the
   // definition and map to that.
   TagDecl *Definition = D->getDefinition();
-  if (Definition && Definition != D) {
+  if (!D->isImplicit() && Definition && Definition != D) {
     Decl *ImportedDef = Importer.Import(Definition);
     if (!ImportedDef)
       return nullptr;
Index: unittests/AST/ASTImporterTest.cpp
===================================================================
--- unittests/AST/ASTImporterTest.cpp
+++ unittests/AST/ASTImporterTest.cpp
@@ -1367,7 +1367,7 @@
 
 TEST_P(
     ASTImporterTestBase,
-    DISABLED_ShouldImportImplicitCXXRecordDeclOfClassTemplateSpecializationDecl) {
+    ShouldImportImplicitCXXRecordDeclOfClassTemplateSpecializationDecl) {
   Decl *From, *To;
   std::tie(From, To) = getImportedDecl(
       R"(