Index: include/clang/AST/DeclTemplate.h
===================================================================
--- include/clang/AST/DeclTemplate.h
+++ include/clang/AST/DeclTemplate.h
@@ -833,6 +833,7 @@
 class FunctionTemplateDecl : public RedeclarableTemplateDecl {
   static void DeallocateCommon(void *Ptr);
 
+  bool IsConcept : 1;
 protected:
   /// \brief Data that is common to all of the declarations of a given
   /// function template.
@@ -980,6 +981,10 @@
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == FunctionTemplate; }
 
+  /// Whether this is a (C++ Concepts TS) function concept.
+  bool isConcept() const { return IsConcept; }
+  void setConcept(bool IC) { IsConcept = IC; }
+
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
 };
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -2068,6 +2068,9 @@
   "'%select{thread_local|inline|friend|constexpr}1'">;
 def err_function_concept_with_params : Error<
   "function concept cannot have any parameters">;
+def err_concept_specified_specialization : Error<
+  "'concept' cannot be applied on an "
+  "%select{explicit instantiation|explicit specialization|partial specialization}0">;
 
 // C++11 char16_t/char32_t
 def warn_cxx98_compat_unicode_type : Warning<
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -5988,6 +5988,16 @@
             << 0 << 3;
         NewVD->setInvalidDecl(true);
       }
+
+      // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
+      // applied only to the definition of a [...] variable template, declared
+      // in namespace scope. [...] A concept definition refers to [...] a
+      // variable concept and its initializer.
+      if (IsVariableTemplateSpecialization) {
+        Diag(D.getDeclSpec().getConceptSpecLoc(),
+             diag::err_concept_specified_specialization)
+          << (IsPartialSpecialization ? 2 : 1);
+      }
     }
   }
 
@@ -7645,6 +7655,10 @@
     }
 
     if (isConcept) {
+      // This is a function concept.
+      if (FunctionTemplateDecl *FTD = NewFD->getDescribedFunctionTemplate())
+        FTD->setConcept(true);
+
       // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
       // applied only to the definition of a function template [...]
       if (!D.isFunctionDefinition()) {
@@ -7703,6 +7717,15 @@
             << 1 << 3;
         NewFD->setInvalidDecl(true);
       }
+
+      // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
+      // applied only to the definition of a function template [...], declared
+      // in namespace scope. [...] A concept definition refers to either a
+      // function concept and its definition [...].
+      if (isFunctionTemplateSpecialization) {
+        Diag(D.getDeclSpec().getConceptSpecLoc(),
+             diag::err_concept_specified_specialization) << 1;
+      }
     }
 
     // If __module_private__ was specified, mark the function accordingly.
@@ -7964,9 +7987,9 @@
                                          TemplateId->NumArgs);
       translateTemplateArguments(TemplateArgsPtr,
                                  TemplateArgs);
-    
+
       HasExplicitTemplateArgs = true;
-    
+
       if (NewFD->isInvalidDecl()) {
         HasExplicitTemplateArgs = false;
       } else if (FunctionTemplate) {
Index: lib/Sema/SemaTemplate.cpp
===================================================================
--- lib/Sema/SemaTemplate.cpp
+++ lib/Sema/SemaTemplate.cpp
@@ -7667,6 +7667,17 @@
     Diag(D.getDeclSpec().getConstexprSpecLoc(),
          diag::err_explicit_instantiation_constexpr);
 
+  // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
+  // applied only to the definition of a function template or variable template,
+  // declared in namespace scope. A concept definition refers to either a
+  // function concept and its definition or a variable concept and its
+  // initializer.
+  if (D.getDeclSpec().isConceptSpecified()) {
+    Diag(D.getDeclSpec().getConceptSpecLoc(),
+         diag:: err_concept_specified_specialization) << 0;
+    return true;
+  }
+
   // C++0x [temp.explicit]p2:
   //   There are two forms of explicit instantiation: an explicit instantiation
   //   definition and an explicit instantiation declaration. An explicit
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
@@ -41,3 +41,20 @@
 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}}
+
+template<typename T> concept bool VCEI { true };
+template concept bool VCEI<int>; // expected-error {{'concept' cannot be applied on an explicit instantiation}}
+extern template concept bool VCEI<int>; // expected-error {{'concept' cannot be applied on an explicit instantiation}}
+
+template<typename T> concept bool VCPS { true };
+template<typename T> concept bool VCPS<T*> { true }; // expected-error {{'concept' cannot be applied on an partial specialization}}
+
+template<typename T> concept bool VCES { true };
+template<> concept bool VCES<int> { true }; // expected-error {{'concept' cannot be applied on an explicit specialization}}
+
+template<typename T> concept bool FCEI() { return true; }
+template concept bool FCEI<int>(); // expected-error {{'concept' cannot be applied on an explicit instantiation}}
+extern template concept bool FCEI<int>(); // expected-error {{'concept' cannot be applied on an explicit instantiation}}
+
+template<typename T> concept bool FCES() { return true; }
+template<> concept bool FCES<bool>() { return true; } // expected-error {{'concept' cannot be applied on an explicit specialization}}