Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -5119,6 +5119,9 @@
   if (D.getDeclSpec().isConstexprSpecified())
     Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_invalid_constexpr)
       << 1;
+  if (D.getDeclSpec().isConceptSpecified())
+    Diag(D.getDeclSpec().getConceptSpecLoc(),
+         diag::err_concept_wrong_decl_kind);
 
   if (D.getName().Kind != UnqualifiedId::IK_Identifier) {
     Diag(D.getName().StartLocation, diag::err_typedef_not_identifier)
@@ -10277,6 +10280,8 @@
   if (DS.isConstexprSpecified())
     Diag(DS.getConstexprSpecLoc(), diag::err_invalid_constexpr)
       << 0;
+  if (DS.isConceptSpecified())
+    Diag(DS.getConceptSpecLoc(), diag::err_concept_wrong_decl_kind);
 
   DiagnoseFunctionSpecifiers(DS);
 
Index: test/CXX/concepts-ts/dcl.dcl/dcl.spec/dcl.spec.concept/p1.cpp
===================================================================
--- test/CXX/concepts-ts/dcl.dcl/dcl.spec/dcl.spec.concept/p1.cpp
+++ test/CXX/concepts-ts/dcl.dcl/dcl.spec/dcl.spec.concept/p1.cpp
@@ -37,5 +37,7 @@
 template <typename T> concept class TCC1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
 template <typename T> concept struct TCS1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
 template <typename T> concept union TCU1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+typedef concept int CI; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+void fpc(concept int i) {} // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
 
 concept bool; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}