Index: cfe/trunk/lib/Sema/SemaTemplate.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaTemplate.cpp
+++ cfe/trunk/lib/Sema/SemaTemplate.cpp
@@ -2052,6 +2052,12 @@
 
 void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,
                                           SourceLocation Loc) {
+  if (CXXRecordDecl *DefRecord =
+          cast<CXXRecordDecl>(Template->getTemplatedDecl())->getDefinition()) {
+    TemplateDecl *DescribedTemplate = DefRecord->getDescribedClassTemplate();
+    Template = DescribedTemplate ? DescribedTemplate : Template;
+  }
+
   DeclContext *DC = Template->getDeclContext();
   if (DC->isDependentContext())
     return;
Index: cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
===================================================================
--- cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
+++ cfe/trunk/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
@@ -489,6 +489,21 @@
 }
 #pragma clang diagnostic pop
 
+namespace PR41549 {
+
+template <class H, class P> struct umm;
+
+template <class H = int, class P = int>
+struct umm {
+  umm(H h = 0, P p = 0);
+};
+
+template <class H, class P> struct umm;
+
+umm m(1);
+
+}
+
 #else
 
 // expected-no-diagnostics