diff --git a/clang/include/clang/Basic/BSC/DiagnosticBSCSemaKinds.td b/clang/include/clang/Basic/BSC/DiagnosticBSCSemaKinds.td
index 6bbd8d5813c625adadafbe04ccb81e81cea00de2..06596c8367305565921260c8a4921d3f3a603e75 100644
--- a/clang/include/clang/Basic/BSC/DiagnosticBSCSemaKinds.td
+++ b/clang/include/clang/Basic/BSC/DiagnosticBSCSemaKinds.td
@@ -82,6 +82,8 @@ def warn_type_has_not_impl_trait : Warning<
   "expected a pointer type which has implemented %0, found %1">,
   InGroup<BSCTraitMissing>;
 def err_trait_is_undefined : Error<"%0 must be defined before it can be used">;
+def err_impl_trait_for_instantiated_type : Error<
+  "cannot impl trait for an instantiated type">;
 
 // BSC generic warnings and errors.
 def err_invalid_struct_definition : Error <
diff --git a/clang/lib/Sema/BSC/SemaBSCTrait.cpp b/clang/lib/Sema/BSC/SemaBSCTrait.cpp
index 64f3b4604086747446ba1f09fca6ca73624a131c..eb89af0024fb37123dbffd6299c4fa276e3aee9d 100644
--- a/clang/lib/Sema/BSC/SemaBSCTrait.cpp
+++ b/clang/lib/Sema/BSC/SemaBSCTrait.cpp
@@ -337,11 +337,22 @@ static bool IsImplTraitDeclIllegal(Sema &S, QualType TraitQT, QualType &ImplQT,
                                    QualType OriginTraitTy) {
   CXXScopeSpec SS;
   NamedDecl *Def = nullptr;
-  Sema::BoundTypeDiagnoser<> Diagnoser(
-      diag::err_typecheck_decl_incomplete_type);
 
-  if (ImplQT->isIncompleteType(&Def))
+  if (ImplQT.getCanonicalType()->isRecordType()) {
+    const RecordDecl *RD =
+        ImplQT.getCanonicalType()->castAs<RecordType>()->getDecl();
+    if (isa<ClassTemplateSpecializationDecl>(RD)) {
+      S.Diag(TypeLoc, diag::err_impl_trait_for_instantiated_type);
+      return true;
+    }
+  }
+
+  if (ImplQT->isIncompleteType(&Def)) {
+    Sema::BoundTypeDiagnoser<> Diagnoser(
+        diag::err_typecheck_decl_incomplete_type);
     Diagnoser.diagnose(S, TypeLoc, ImplQT);
+    return true;
+  }
 
   IdentifierInfo *FunctionID = nullptr;
   RecordDecl *VT = TD->getVtable();
diff --git a/clang/test/BSC/Negative/Generic/StructAndFunction/generic_type_without_tag/generic_type_without_tag.cbs b/clang/test/BSC/Negative/Generic/StructAndFunction/generic_type_without_tag/generic_type_without_tag.cbs
index 2ef48bdc28718882c4c6582982a84ef78071ae3d..5f13faf9e4861f7bcd419e5c4c4443fd17d3465b 100644
--- a/clang/test/BSC/Negative/Generic/StructAndFunction/generic_type_without_tag/generic_type_without_tag.cbs
+++ b/clang/test/BSC/Negative/Generic/StructAndFunction/generic_type_without_tag/generic_type_without_tag.cbs
@@ -5,7 +5,7 @@ void S<int>::foo(This* this) {}  // expected-error {{extended type of a BSC memb
 
 trait F {};
 impl trait F for S<T>; // expected-error {{use of undeclared identifier 'T'}}
-impl trait F for S<int>; // expected-error {{variable has incomplete type 'struct S<int>'}}
+impl trait F for S<int>; // expected-error {{cannot impl trait for an instantiated type}}
 
 void struct S<T>::foo1(This* this) {} // expected-note {{previous definition is here}}
 
diff --git a/clang/test/BSC/Negative/Trait/r3/impl_trait_for_generic_type/impl_trait_for_generic_type.cbs b/clang/test/BSC/Negative/Trait/r3/impl_trait_for_generic_type/impl_trait_for_generic_type.cbs
new file mode 100644
index 0000000000000000000000000000000000000000..a5c2022fde4f0fb656c28696be4f5c74d68655c8
--- /dev/null
+++ b/clang/test/BSC/Negative/Trait/r3/impl_trait_for_generic_type/impl_trait_for_generic_type.cbs
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+trait F{};
+
+struct S<T> {};
+union U<T> {};
+impl trait F for S<T>; // expected-error {{use of undeclared identifier 'T'}}
+impl trait F for struct S<T>; // expected-error {{use of undeclared identifier 'T'}}
+impl trait F for S<int>; // expected-error {{cannot impl trait for an instantiated type}}
+impl trait F for struct S<int>; // expected-error {{cannot impl trait for an instantiated type}}
+impl trait F for U<T>; // expected-error {{use of undeclared identifier 'T'}}
+impl trait F for union U<T>; // expected-error {{use of undeclared identifier 'T'}}
+impl trait F for U<int>; // expected-error {{cannot impl trait for an instantiated type}}
+impl trait F for union U<int>; // expected-error {{cannot impl trait for an instantiated type}}
+
+owned struct K<T> {};
+impl trait F for K<T>; // expected-error {{use of undeclared identifier 'T'}}
+impl trait F for K<int>; // expected-error {{cannot impl trait for an instantiated type}}
+
+struct M {
+    U<int> u;
+    S<int> s;
+    K<int> k;
+};
+impl trait F for U<int>; // expected-error {{cannot impl trait for an instantiated type}}
+impl trait F for union U<int>; // expected-error {{cannot impl trait for an instantiated type}}
+impl trait F for S<int>; // expected-error {{cannot impl trait for an instantiated type}}
+impl trait F for struct S<int>; // expected-error {{cannot impl trait for an instantiated type}}
+impl trait F for K<int>; // expected-error {{cannot impl trait for an instantiated type}}
\ No newline at end of file