diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -11023,9 +11023,12 @@
       TemplateName SpecifiedName = RetTST.getTypePtr()->getTemplateName();
       bool TemplateMatches =
           Context.hasSameTemplateName(SpecifiedName, GuidedTemplate);
-      // FIXME: We should consider other template kinds (using, qualified),
-      // otherwise we will emit bogus diagnostics.
-      if (SpecifiedName.getKind() == TemplateName::Template && TemplateMatches)
+      auto TKind = SpecifiedName.getKind();
+      // Template names within TemplateSpecializationType are never qualified
+      // template names!
+      if ((TKind == TemplateName::Template ||
+           TKind == TemplateName::UsingTemplate) &&
+          TemplateMatches)
         AcceptableReturnType = true;
       else {
         // This could still instantiate to the right type, unless we know it
diff --git a/clang/test/CXX/temp/temp.deduct.guide/p3.cpp b/clang/test/CXX/temp/temp.deduct.guide/p3.cpp
--- a/clang/test/CXX/temp/temp.deduct.guide/p3.cpp
+++ b/clang/test/CXX/temp/temp.deduct.guide/p3.cpp
@@ -55,8 +55,6 @@
   }
   using N::NamedNS1;
   NamedNS1(int) -> NamedNS1<int>; // expected-error {{deduction guide must be declared in the same scope as template}}
-  // FIXME: remove the following bogus diagnostic
-  // expected-error@-2{{deduction guide is not written as a specialization of template 'NamedNS1'}}
 
   using namespace N;
   NamedNS2(int) -> NamedNS2<int>; // expected-error {{deduction guide must be declared in the same scope as template}}