diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5336208d0..ae5990ebe 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,7 +67,7 @@ if(NOT DEFINED CMAKE_CXX_STANDARD AND NOT CMake_NO_CXX_STANDARD)
   endif()
 endif()
 if(NOT CMake_TEST_EXTERNAL_CMAKE)
-  include(${CMake_SOURCE_DIR}/Source/Checks/cm_cxx11_unordered_map.cmake)
+  include(${CMake_SOURCE_DIR}/Source/Checks/cm_cxx_features.cmake)
 endif()
 
 # option to set the internal encoding of CMake to UTF-8
diff --git a/Source/CPack/IFW/cmCPackIFWRepository.cxx b/Source/CPack/IFW/cmCPackIFWRepository.cxx
index b8a10c64a..e4fa569b1 100644
--- a/Source/CPack/IFW/cmCPackIFWRepository.cxx
+++ b/Source/CPack/IFW/cmCPackIFWRepository.cxx
@@ -177,7 +177,7 @@ public:
   bool patched;
 
 protected:
-  virtual void StartElement(const std::string& name, const char** atts)
+  void StartElement(const std::string& name, const char** atts) CM_OVERRIDE
   {
     xout.StartElement(name);
     StartFragment(atts);
@@ -192,7 +192,7 @@ protected:
     }
   }
 
-  virtual void EndElement(const std::string& name)
+  void EndElement(const std::string& name) CM_OVERRIDE
   {
     if (name == "Updates" && !patched) {
       repository->WriteRepositoryUpdates(xout);
@@ -208,7 +208,7 @@ protected:
     }
   }
 
-  virtual void CharacterDataHandler(const char* data, int length)
+  void CharacterDataHandler(const char* data, int length) CM_OVERRIDE
   {
     std::string content(data, data + length);
     if (content == "" || content == " " || content == "  " ||
diff --git a/Source/CTest/cmCTestBZR.cxx b/Source/CTest/cmCTestBZR.cxx
index 92eb570f5..5b3f6128a 100644
--- a/Source/CTest/cmCTestBZR.cxx
+++ b/Source/CTest/cmCTestBZR.cxx
@@ -101,7 +101,7 @@ private:
   bool CheckOutFound;
   cmsys::RegularExpression RegexCheckOut;
   cmsys::RegularExpression RegexParent;
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexCheckOut.find(this->Line)) {
       this->BZR->URL = this->RegexCheckOut.match(1);
@@ -126,7 +126,7 @@ public:
 private:
   std::string& Rev;
   cmsys::RegularExpression RegexRevno;
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexRevno.find(this->Line)) {
       this->Rev = this->RegexRevno.match(1);
@@ -185,7 +185,7 @@ public:
   }
   ~LogParser() { this->CleanupParser(); }
 
-  virtual int InitializeParser()
+  int InitializeParser() CM_OVERRIDE
   {
     int res = cmXMLParser::InitializeParser();
     if (res) {
@@ -207,14 +207,14 @@ private:
 
   cmsys::RegularExpression EmailRegex;
 
-  virtual bool ProcessChunk(const char* data, int length)
+  bool ProcessChunk(const char* data, int length) CM_OVERRIDE
   {
     this->OutputLogger::ProcessChunk(data, length);
     this->ParseChunk(data, length);
     return true;
   }
 
-  virtual void StartElement(const std::string& name, const char**)
+  void StartElement(const std::string& name, const char**) CM_OVERRIDE
   {
     this->CData.clear();
     if (name == "log") {
@@ -239,12 +239,12 @@ private:
     }
   }
 
-  virtual void CharacterDataHandler(const char* data, int length)
+  void CharacterDataHandler(const char* data, int length) CM_OVERRIDE
   {
     this->CData.insert(this->CData.end(), data, data + length);
   }
 
-  virtual void EndElement(const std::string& name)
+  void EndElement(const std::string& name) CM_OVERRIDE
   {
     if (name == "log") {
       this->BZR->DoRevision(this->Rev, this->Changes);
@@ -274,7 +274,7 @@ private:
     this->CData.clear();
   }
 
-  virtual void ReportError(int, int, const char* msg)
+  void ReportError(int, int, const char* msg) CM_OVERRIDE
   {
     this->BZR->Log << "Error parsing bzr log xml: " << msg << "\n";
   }
@@ -294,7 +294,7 @@ private:
   cmCTestBZR* BZR;
   cmsys::RegularExpression RegexUpdate;
 
-  virtual bool ProcessChunk(const char* first, int length)
+  bool ProcessChunk(const char* first, int length) CM_OVERRIDE
   {
     bool last_is_new_line = (*first == '\r' || *first == '\n');
 
@@ -325,7 +325,7 @@ private:
     return true;
   }
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexUpdate.find(this->Line)) {
       this->DoPath(this->RegexUpdate.match(1)[0],
@@ -431,7 +431,7 @@ public:
 private:
   cmCTestBZR* BZR;
   cmsys::RegularExpression RegexStatus;
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexStatus.find(this->Line)) {
       this->DoPath(this->RegexStatus.match(1)[0],
diff --git a/Source/CTest/cmCTestCVS.cxx b/Source/CTest/cmCTestCVS.cxx
index 5ddafbb9c..df1968504 100644
--- a/Source/CTest/cmCTestCVS.cxx
+++ b/Source/CTest/cmCTestCVS.cxx
@@ -53,7 +53,7 @@ private:
   cmsys::RegularExpression RegexFileRemoved1;
   cmsys::RegularExpression RegexFileRemoved2;
 
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexFileUpdated.find(this->Line)) {
       this->DoFile(PathUpdated, this->RegexFileUpdated.match(2));
@@ -140,7 +140,7 @@ private:
   SectionType Section;
   Revision Rev;
 
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->Line == ("======================================="
                        "======================================")) {
diff --git a/Source/CTest/cmCTestGIT.cxx b/Source/CTest/cmCTestGIT.cxx
index 8b392f29e..36a781e9e 100644
--- a/Source/CTest/cmCTestGIT.cxx
+++ b/Source/CTest/cmCTestGIT.cxx
@@ -52,7 +52,7 @@ public:
 
 private:
   std::string& Line1;
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     // Only the first line is of interest.
     this->Line1 = this->Line;
@@ -355,7 +355,7 @@ protected:
     this->Changes.clear();
   }
 
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->Line[0] == ':') {
       this->DiffField = DiffFieldChange;
@@ -513,7 +513,7 @@ private:
     person.TimeZone = strtol(c, (char**)&c, 10);
   }
 
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->Line.empty()) {
       if (this->Section == SectionBody && this->LineEnd == '\0') {
diff --git a/Source/CTest/cmCTestHG.cxx b/Source/CTest/cmCTestHG.cxx
index f1fe3774c..9589e057e 100644
--- a/Source/CTest/cmCTestHG.cxx
+++ b/Source/CTest/cmCTestHG.cxx
@@ -41,7 +41,7 @@ private:
   std::string& Rev;
   cmsys::RegularExpression RegexIdentify;
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexIdentify.find(this->Line)) {
       this->Rev = this->RegexIdentify.match(1);
@@ -65,7 +65,7 @@ private:
   cmCTestHG* HG;
   cmsys::RegularExpression RegexStatus;
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexStatus.find(this->Line)) {
       this->DoPath(this->RegexStatus.match(1)[0], this->RegexStatus.match(2));
@@ -182,14 +182,14 @@ private:
   Change CurChange;
   std::vector<char> CData;
 
-  virtual bool ProcessChunk(const char* data, int length)
+  bool ProcessChunk(const char* data, int length) CM_OVERRIDE
   {
     this->OutputLogger::ProcessChunk(data, length);
     this->ParseChunk(data, length);
     return true;
   }
 
-  virtual void StartElement(const std::string& name, const char** atts)
+  void StartElement(const std::string& name, const char** atts) CM_OVERRIDE
   {
     this->CData.clear();
     if (name == "logentry") {
@@ -201,12 +201,12 @@ private:
     }
   }
 
-  virtual void CharacterDataHandler(const char* data, int length)
+  void CharacterDataHandler(const char* data, int length) CM_OVERRIDE
   {
     this->CData.insert(this->CData.end(), data, data + length);
   }
 
-  virtual void EndElement(const std::string& name)
+  void EndElement(const std::string& name) CM_OVERRIDE
   {
     if (name == "logentry") {
       this->HG->DoRevision(this->Rev, this->Changes);
@@ -261,7 +261,7 @@ private:
     return output;
   }
 
-  virtual void ReportError(int, int, const char* msg)
+  void ReportError(int, int, const char* msg) CM_OVERRIDE
   {
     this->HG->Log << "Error parsing hg log xml: " << msg << "\n";
   }
diff --git a/Source/CTest/cmCTestMemCheckHandler.cxx b/Source/CTest/cmCTestMemCheckHandler.cxx
index 5f70f66df..6f1a2c495 100644
--- a/Source/CTest/cmCTestMemCheckHandler.cxx
+++ b/Source/CTest/cmCTestMemCheckHandler.cxx
@@ -61,7 +61,7 @@ public:
     this->CTest = c;
     this->SetErrorCallback(xmlReportError, (void*)c);
   }
-  void StartElement(const std::string& name, const char** atts)
+  void StartElement(const std::string& name, const char** atts) CM_OVERRIDE
   {
     if (name == "MemoryLeak" || name == "ResourceLeak") {
       this->Errors.push_back(cmCTestMemCheckHandler::MLK);
@@ -78,7 +78,7 @@ public:
     ostr << "\n";
     this->Log += ostr.str();
   }
-  void EndElement(const std::string&) {}
+  void EndElement(const std::string&) CM_OVERRIDE {}
 
   const char* GetAttribute(const char* name, const char** atts)
   {
diff --git a/Source/CTest/cmCTestP4.cxx b/Source/CTest/cmCTestP4.cxx
index ede11c990..072da29f7 100644
--- a/Source/CTest/cmCTestP4.cxx
+++ b/Source/CTest/cmCTestP4.cxx
@@ -45,7 +45,7 @@ private:
   std::string& Rev;
   cmsys::RegularExpression RegexIdentify;
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexIdentify.find(this->Line)) {
       this->Rev = this->RegexIdentify.match(1);
@@ -69,7 +69,7 @@ private:
   cmsys::RegularExpression RegexIdentify;
   cmCTestP4* P4;
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexIdentify.find(this->Line)) {
       P4->ChangeLists.push_back(this->RegexIdentify.match(1));
@@ -92,7 +92,7 @@ private:
   cmsys::RegularExpression RegexUser;
   cmCTestP4* P4;
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexUser.find(this->Line)) {
       User NewUser;
@@ -135,7 +135,7 @@ private:
   std::string CurrentPath;
   cmsys::RegularExpression RegexDiff;
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (!this->Line.empty() && this->Line[0] == '=' &&
         this->RegexDiff.find(this->Line)) {
@@ -225,7 +225,7 @@ private:
   SectionType Section;
   Revision Rev;
 
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->Line.empty()) {
       this->NextSection();
diff --git a/Source/CTest/cmCTestSVN.cxx b/Source/CTest/cmCTestSVN.cxx
index fa014111b..074bd3df7 100644
--- a/Source/CTest/cmCTestSVN.cxx
+++ b/Source/CTest/cmCTestSVN.cxx
@@ -62,7 +62,7 @@ private:
   cmsys::RegularExpression RegexRev;
   cmsys::RegularExpression RegexURL;
   cmsys::RegularExpression RegexRoot;
-  virtual bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexRev.find(this->Line)) {
       this->Rev = this->RegexRev.match(1);
@@ -206,7 +206,7 @@ private:
   cmCTestSVN* SVN;
   cmsys::RegularExpression RegexUpdate;
 
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexUpdate.find(this->Line)) {
       this->DoPath(this->RegexUpdate.match(1)[0],
@@ -323,14 +323,14 @@ private:
   Change CurChange;
   std::vector<char> CData;
 
-  virtual bool ProcessChunk(const char* data, int length)
+  bool ProcessChunk(const char* data, int length) CM_OVERRIDE
   {
     this->OutputLogger::ProcessChunk(data, length);
     this->ParseChunk(data, length);
     return true;
   }
 
-  virtual void StartElement(const std::string& name, const char** atts)
+  void StartElement(const std::string& name, const char** atts) CM_OVERRIDE
   {
     this->CData.clear();
     if (name == "logentry") {
@@ -348,12 +348,12 @@ private:
     }
   }
 
-  virtual void CharacterDataHandler(const char* data, int length)
+  void CharacterDataHandler(const char* data, int length) CM_OVERRIDE
   {
     this->CData.insert(this->CData.end(), data, data + length);
   }
 
-  virtual void EndElement(const std::string& name)
+  void EndElement(const std::string& name) CM_OVERRIDE
   {
     if (name == "logentry") {
       this->SVN->DoRevisionSVN(this->Rev, this->Changes);
@@ -372,7 +372,7 @@ private:
     this->CData.clear();
   }
 
-  virtual void ReportError(int, int, const char* msg)
+  void ReportError(int, int, const char* msg) CM_OVERRIDE
   {
     this->SVN->Log << "Error parsing svn log xml: " << msg << "\n";
   }
@@ -441,7 +441,7 @@ public:
 private:
   cmCTestSVN* SVN;
   cmsys::RegularExpression RegexStatus;
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexStatus.find(this->Line)) {
       this->DoPath(this->RegexStatus.match(1)[0],
@@ -506,7 +506,7 @@ public:
 private:
   cmCTestSVN* SVN;
   cmsys::RegularExpression RegexExternal;
-  bool ProcessLine()
+  bool ProcessLine() CM_OVERRIDE
   {
     if (this->RegexExternal.find(this->Line)) {
       this->DoPath(this->RegexExternal.match(1));
diff --git a/Source/CTest/cmCTestScriptHandler.cxx b/Source/CTest/cmCTestScriptHandler.cxx
index 6389a9db3..028cfdd20 100644
--- a/Source/CTest/cmCTestScriptHandler.cxx
+++ b/Source/CTest/cmCTestScriptHandler.cxx
@@ -60,8 +60,8 @@ class cmCTestScriptFunctionBlocker : public cmFunctionBlocker
 public:
   cmCTestScriptFunctionBlocker() {}
   virtual ~cmCTestScriptFunctionBlocker() {}
-  virtual bool IsFunctionBlocked(const cmListFileFunction& lff, cmMakefile& mf,
-                                 cmExecutionStatus&);
+  bool IsFunctionBlocked(const cmListFileFunction& lff, cmMakefile& mf,
+                         cmExecutionStatus&) CM_OVERRIDE;
   // virtual bool ShouldRemove(const cmListFileFunction& lff, cmMakefile &mf);
   // virtual void ScopeEnded(cmMakefile &mf);
 
diff --git a/Source/CTest/cmCTestSubmitHandler.cxx b/Source/CTest/cmCTestSubmitHandler.cxx
index 69f2ac5b0..85e243f5c 100644
--- a/Source/CTest/cmCTestSubmitHandler.cxx
+++ b/Source/CTest/cmCTestSubmitHandler.cxx
@@ -69,7 +69,7 @@ private:
     return val;
   }
 
-  virtual void StartElement(const std::string& name, const char** atts)
+  void StartElement(const std::string& name, const char** atts) CM_OVERRIDE
   {
     this->CurrentValue.clear();
     if (name == "cdash") {
@@ -77,12 +77,12 @@ private:
     }
   }
 
-  virtual void CharacterDataHandler(const char* data, int length)
+  void CharacterDataHandler(const char* data, int length) CM_OVERRIDE
   {
     this->CurrentValue.insert(this->CurrentValue.end(), data, data + length);
   }
 
-  virtual void EndElement(const std::string& name)
+  void EndElement(const std::string& name) CM_OVERRIDE
   {
     if (name == "status") {
       std::string status = cmSystemTools::UpperCase(this->GetCurrentValue());
diff --git a/Source/CTest/cmCTestTestHandler.cxx b/Source/CTest/cmCTestTestHandler.cxx
index c991a23f4..3ee9c5f97 100644
--- a/Source/CTest/cmCTestTestHandler.cxx
+++ b/Source/CTest/cmCTestTestHandler.cxx
@@ -42,7 +42,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone()
+  cmCommand* Clone() CM_OVERRIDE
   {
     cmCTestSubdirCommand* c = new cmCTestSubdirCommand;
     c->TestHandler = this->TestHandler;
@@ -53,13 +53,13 @@ public:
    * This is called when the command is first encountered in
    * the CMakeLists.txt file.
    */
-  virtual bool InitialPass(std::vector<std::string> const& args,
-                           cmExecutionStatus&);
+  bool InitialPass(std::vector<std::string> const& args,
+                   cmExecutionStatus&) CM_OVERRIDE;
 
   /**
    * The name of the command as specified in CMakeList.txt.
    */
-  virtual std::string GetName() const { return "subdirs"; }
+  std::string GetName() const CM_OVERRIDE { return "subdirs"; }
 
   cmTypeMacro(cmCTestSubdirCommand, cmCommand);
 
@@ -123,7 +123,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone()
+  cmCommand* Clone() CM_OVERRIDE
   {
     cmCTestAddSubdirectoryCommand* c = new cmCTestAddSubdirectoryCommand;
     c->TestHandler = this->TestHandler;
@@ -134,13 +134,13 @@ public:
    * This is called when the command is first encountered in
    * the CMakeLists.txt file.
    */
-  virtual bool InitialPass(std::vector<std::string> const& args,
-                           cmExecutionStatus&);
+  bool InitialPass(std::vector<std::string> const& args,
+                   cmExecutionStatus&) CM_OVERRIDE;
 
   /**
    * The name of the command as specified in CMakeList.txt.
    */
-  virtual std::string GetName() const { return "add_subdirectory"; }
+  std::string GetName() const CM_OVERRIDE { return "add_subdirectory"; }
 
   cmTypeMacro(cmCTestAddSubdirectoryCommand, cmCommand);
 
@@ -197,7 +197,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone()
+  cmCommand* Clone() CM_OVERRIDE
   {
     cmCTestAddTestCommand* c = new cmCTestAddTestCommand;
     c->TestHandler = this->TestHandler;
@@ -208,13 +208,13 @@ public:
    * This is called when the command is first encountered in
    * the CMakeLists.txt file.
    */
-  virtual bool InitialPass(std::vector<std::string> const&,
-                           cmExecutionStatus&);
+  bool InitialPass(std::vector<std::string> const&,
+                   cmExecutionStatus&) CM_OVERRIDE;
 
   /**
    * The name of the command as specified in CMakeList.txt.
    */
-  virtual std::string GetName() const { return "add_test"; }
+  std::string GetName() const CM_OVERRIDE { return "add_test"; }
 
   cmTypeMacro(cmCTestAddTestCommand, cmCommand);
 
@@ -237,7 +237,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone()
+  cmCommand* Clone() CM_OVERRIDE
   {
     cmCTestSetTestsPropertiesCommand* c = new cmCTestSetTestsPropertiesCommand;
     c->TestHandler = this->TestHandler;
@@ -248,13 +248,13 @@ public:
    * This is called when the command is first encountered in
    * the CMakeLists.txt file.
   */
-  virtual bool InitialPass(std::vector<std::string> const&,
-                           cmExecutionStatus&);
+  bool InitialPass(std::vector<std::string> const&,
+                   cmExecutionStatus&) CM_OVERRIDE;
 
   /**
    * The name of the command as specified in CMakeList.txt.
    */
-  virtual std::string GetName() const { return "set_tests_properties"; }
+  std::string GetName() const CM_OVERRIDE { return "set_tests_properties"; }
 
   cmTypeMacro(cmCTestSetTestsPropertiesCommand, cmCommand);
 
diff --git a/Source/CTest/cmParseCoberturaCoverage.cxx b/Source/CTest/cmParseCoberturaCoverage.cxx
index 3bdae179c..f1c37edcb 100644
--- a/Source/CTest/cmParseCoberturaCoverage.cxx
+++ b/Source/CTest/cmParseCoberturaCoverage.cxx
@@ -23,7 +23,7 @@ public:
   virtual ~XMLParser() {}
 
 protected:
-  virtual void EndElement(const std::string& name)
+  void EndElement(const std::string& name) CM_OVERRIDE
   {
     if (name == "source") {
       this->InSource = false;
@@ -34,7 +34,7 @@ protected:
     }
   }
 
-  virtual void CharacterDataHandler(const char* data, int length)
+  void CharacterDataHandler(const char* data, int length) CM_OVERRIDE
   {
     std::string tmp;
     tmp.insert(0, data, length);
@@ -46,7 +46,7 @@ protected:
     }
   }
 
-  virtual void StartElement(const std::string& name, const char** atts)
+  void StartElement(const std::string& name, const char** atts) CM_OVERRIDE
   {
     std::string FoundSource;
     std::string finalpath = "";
diff --git a/Source/CTest/cmParseJacocoCoverage.cxx b/Source/CTest/cmParseJacocoCoverage.cxx
index e456f39f9..27ccf5832 100644
--- a/Source/CTest/cmParseJacocoCoverage.cxx
+++ b/Source/CTest/cmParseJacocoCoverage.cxx
@@ -23,9 +23,9 @@ public:
   virtual ~XMLParser() {}
 
 protected:
-  virtual void EndElement(const std::string&) {}
+  void EndElement(const std::string&) CM_OVERRIDE {}
 
-  virtual void StartElement(const std::string& name, const char** atts)
+  void StartElement(const std::string& name, const char** atts) CM_OVERRIDE
   {
     if (name == "package") {
       this->PackageName = atts[1];
diff --git a/Source/Checks/cm_cxx11_unordered_map.cmake b/Source/Checks/cm_cxx11_unordered_map.cmake
deleted file mode 100644
index 80fe391bc..000000000
--- a/Source/Checks/cm_cxx11_unordered_map.cmake
+++ /dev/null
@@ -1,25 +0,0 @@
-
-if(CMAKE_CXX_STANDARD AND NOT DEFINED CMake_HAVE_CXX11_UNORDERED_MAP)
-  message(STATUS "Checking if compiler supports C++11 unordered_map")
-  try_compile(CMake_HAVE_CXX11_UNORDERED_MAP
-    ${CMAKE_CURRENT_BINARY_DIR}
-    ${CMAKE_CURRENT_LIST_DIR}/cm_cxx11_unordered_map.cpp
-    CMAKE_FLAGS -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
-    OUTPUT_VARIABLE OUTPUT
-    )
-  if(CMake_HAVE_CXX11_UNORDERED_MAP)
-    message(STATUS "Checking if compiler supports C++11 unordered_map - yes")
-    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
-      "Determining if compiler supports C++11 unordered_map passed with the following output:\n"
-      "${OUTPUT}\n"
-      "\n"
-      )
-  else()
-    message(STATUS "Checking if compiler supports C++11 unordered_map - no")
-    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
-      "Determining if compiler supports C++11 unordered_map failed with the following output:\n"
-      "${OUTPUT}\n"
-      "\n"
-      )
-  endif()
-endif()
diff --git a/Source/Checks/cm_cxx_features.cmake b/Source/Checks/cm_cxx_features.cmake
new file mode 100644
index 000000000..18dbaf8a1
--- /dev/null
+++ b/Source/Checks/cm_cxx_features.cmake
@@ -0,0 +1,38 @@
+
+function(cm_check_cxx_feature name)
+  string(TOUPPER ${name} FEATURE)
+  if(NOT DEFINED CMake_HAVE_CXX_${FEATURE})
+    message(STATUS "Checking if compiler supports C++ ${name}")
+    try_compile(CMake_HAVE_CXX_${FEATURE}
+      ${CMAKE_CURRENT_BINARY_DIR}
+      ${CMAKE_CURRENT_LIST_DIR}/cm_cxx_${name}.cxx
+      CMAKE_FLAGS -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
+      OUTPUT_VARIABLE OUTPUT
+      )
+    # If using the feature causes warnings, treat it as broken/unavailable.
+    if(OUTPUT MATCHES "warning")
+      set(CMake_HAVE_CXX_${FEATURE} OFF CACHE INTERNAL "TRY_COMPILE" FORCE)
+    endif()
+    if(CMake_HAVE_CXX_${FEATURE})
+      message(STATUS "Checking if compiler supports C++ ${name} - yes")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+        "Determining if compiler supports C++ ${name} passed with the following output:\n"
+        "${OUTPUT}\n"
+        "\n"
+        )
+    else()
+      message(STATUS "Checking if compiler supports C++ ${name} - no")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+        "Determining if compiler supports C++ ${name} failed with the following output:\n"
+        "${OUTPUT}\n"
+        "\n"
+        )
+    endif()
+  endif()
+endfunction()
+
+if(CMAKE_CXX_STANDARD)
+  cm_check_cxx_feature(override)
+  cm_check_cxx_feature(unordered_map)
+  cm_check_cxx_feature(unordered_set)
+endif()
diff --git a/Source/Checks/cm_cxx_override.cxx b/Source/Checks/cm_cxx_override.cxx
new file mode 100644
index 000000000..9395a0a23
--- /dev/null
+++ b/Source/Checks/cm_cxx_override.cxx
@@ -0,0 +1,20 @@
+struct Foo
+{
+  virtual int test() const = 0;
+};
+
+struct Bar : Foo
+{
+  int test() const override { return 0; }
+};
+
+int test(Foo const& foo)
+{
+  return foo.test();
+}
+
+int main()
+{
+  Bar const bar;
+  return test(bar);
+}
diff --git a/Source/Checks/cm_cxx11_unordered_map.cpp b/Source/Checks/cm_cxx_unordered_map.cxx
similarity index 100%
rename from Source/Checks/cm_cxx11_unordered_map.cpp
rename to Source/Checks/cm_cxx_unordered_map.cxx
diff --git a/Source/Checks/cm_cxx_unordered_set.cxx b/Source/Checks/cm_cxx_unordered_set.cxx
new file mode 100644
index 000000000..de4bb7765
--- /dev/null
+++ b/Source/Checks/cm_cxx_unordered_set.cxx
@@ -0,0 +1,7 @@
+#include <unordered_set>
+int main()
+{
+  std::unordered_set<int> set;
+  set.insert(0);
+  return 0;
+}
diff --git a/Source/cmConfigure.cmake.h.in b/Source/cmConfigure.cmake.h.in
index 938b10ed4..a8d4f58c6 100644
--- a/Source/cmConfigure.cmake.h.in
+++ b/Source/cmConfigure.cmake.h.in
@@ -29,8 +29,16 @@
 #cmakedefine CMAKE_USE_ELF_PARSER
 #cmakedefine CMAKE_USE_MACH_PARSER
 #cmakedefine CMAKE_ENCODING_UTF8
-#cmakedefine CMake_HAVE_CXX11_UNORDERED_MAP
+#cmakedefine CMake_HAVE_CXX_OVERRIDE
+#cmakedefine CMake_HAVE_CXX_UNORDERED_MAP
+#cmakedefine CMake_HAVE_CXX_UNORDERED_SET
 #define CMAKE_BIN_DIR "/@CMAKE_BIN_DIR@"
 #define CMAKE_DATA_DIR "/@CMAKE_DATA_DIR@"
 
+#ifdef CMake_HAVE_CXX_OVERRIDE
+#define CM_OVERRIDE override
+#else
+#define CM_OVERRIDE
+#endif
+
 #endif
diff --git a/Source/cmDefinitions.h b/Source/cmDefinitions.h
index 7be0098eb..8f1813c98 100644
--- a/Source/cmDefinitions.h
+++ b/Source/cmDefinitions.h
@@ -17,7 +17,7 @@
 #include "cmLinkedTree.h"
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include "cmsys/hash_map.hxx"
@@ -92,7 +92,7 @@ private:
   static Def NoDef;
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, Def> MapType;
 #else
   typedef cmsys::hash_map<std::string, Def> MapType;
diff --git a/Source/cmELF.cxx b/Source/cmELF.cxx
index c7f8a2d62..16294ea46 100644
--- a/Source/cmELF.cxx
+++ b/Source/cmELF.cxx
@@ -241,20 +241,20 @@ public:
                     ByteOrderType order);
 
   // Return the number of sections as specified by the ELF header.
-  virtual unsigned int GetNumberOfSections() const
+  unsigned int GetNumberOfSections() const CM_OVERRIDE
   {
     return static_cast<unsigned int>(this->ELFHeader.e_shnum);
   }
 
   // Get the file position and size of a dynamic section entry.
-  virtual unsigned int GetDynamicEntryCount();
-  virtual unsigned long GetDynamicEntryPosition(int j);
+  unsigned int GetDynamicEntryCount() CM_OVERRIDE;
+  unsigned long GetDynamicEntryPosition(int j) CM_OVERRIDE;
 
   // Lookup a string from the dynamic section with the given tag.
-  virtual StringEntry const* GetDynamicSectionString(unsigned int tag);
+  StringEntry const* GetDynamicSectionString(unsigned int tag) CM_OVERRIDE;
 
   // Print information about the ELF file.
-  virtual void PrintInfo(std::ostream& os) const
+  void PrintInfo(std::ostream& os) const CM_OVERRIDE
   {
     os << "ELF " << Types::GetName();
     if (this->ByteOrder == ByteOrderMSB) {
diff --git a/Source/cmFileTimeComparison.cxx b/Source/cmFileTimeComparison.cxx
index 7efe1943e..9d6350528 100644
--- a/Source/cmFileTimeComparison.cxx
+++ b/Source/cmFileTimeComparison.cxx
@@ -13,7 +13,7 @@
 
 // Use a hash table to avoid duplicate file time checks from disk.
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -47,13 +47,13 @@ private:
   {
   public:
     size_t operator()(const std::string& s) const { return h(s.c_str()); }
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
     std::hash<const char*> h;
 #else
     cmsys::hash<const char*> h;
 #endif
   };
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string,
 #else
   typedef cmsys::hash_map<std::string,
diff --git a/Source/cmGeneratorExpressionNode.cxx b/Source/cmGeneratorExpressionNode.cxx
index e750551b2..599ea8d3a 100644
--- a/Source/cmGeneratorExpressionNode.cxx
+++ b/Source/cmGeneratorExpressionNode.cxx
@@ -42,14 +42,14 @@ static const struct ZeroNode : public cmGeneratorExpressionNode
 {
   ZeroNode() {}
 
-  virtual bool GeneratesContent() const { return false; }
+  bool GeneratesContent() const CM_OVERRIDE { return false; }
 
-  virtual bool AcceptsArbitraryContentParameter() const { return true; }
+  bool AcceptsArbitraryContentParameter() const CM_OVERRIDE { return true; }
 
   std::string Evaluate(const std::vector<std::string>&,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return std::string();
   }
@@ -59,12 +59,12 @@ static const struct OneNode : public cmGeneratorExpressionNode
 {
   OneNode() {}
 
-  virtual bool AcceptsArbitraryContentParameter() const { return true; }
+  bool AcceptsArbitraryContentParameter() const CM_OVERRIDE { return true; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return parameters.front();
   }
@@ -113,7 +113,7 @@ static const struct NotNode : public cmGeneratorExpressionNode
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     if (*parameters.begin() != "0" && *parameters.begin() != "1") {
       reportError(
@@ -129,12 +129,12 @@ static const struct BoolNode : public cmGeneratorExpressionNode
 {
   BoolNode() {}
 
-  virtual int NumExpectedParameters() const { return 1; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 1; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return !cmSystemTools::IsOff(parameters.begin()->c_str()) ? "1" : "0";
   }
@@ -144,12 +144,12 @@ static const struct StrEqualNode : public cmGeneratorExpressionNode
 {
   StrEqualNode() {}
 
-  virtual int NumExpectedParameters() const { return 2; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 2; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return *parameters.begin() == parameters[1] ? "1" : "0";
   }
@@ -159,12 +159,12 @@ static const struct EqualNode : public cmGeneratorExpressionNode
 {
   EqualNode() {}
 
-  virtual int NumExpectedParameters() const { return 2; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 2; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     char* pEnd;
 
@@ -236,12 +236,12 @@ static const struct LowerCaseNode : public cmGeneratorExpressionNode
 {
   LowerCaseNode() {}
 
-  bool AcceptsArbitraryContentParameter() const { return true; }
+  bool AcceptsArbitraryContentParameter() const CM_OVERRIDE { return true; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return cmSystemTools::LowerCase(parameters.front());
   }
@@ -251,12 +251,12 @@ static const struct UpperCaseNode : public cmGeneratorExpressionNode
 {
   UpperCaseNode() {}
 
-  bool AcceptsArbitraryContentParameter() const { return true; }
+  bool AcceptsArbitraryContentParameter() const CM_OVERRIDE { return true; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return cmSystemTools::UpperCase(parameters.front());
   }
@@ -266,12 +266,12 @@ static const struct MakeCIdentifierNode : public cmGeneratorExpressionNode
 {
   MakeCIdentifierNode() {}
 
-  bool AcceptsArbitraryContentParameter() const { return true; }
+  bool AcceptsArbitraryContentParameter() const CM_OVERRIDE { return true; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return cmSystemTools::MakeCidentifier(parameters.front());
   }
@@ -281,12 +281,12 @@ static const struct Angle_RNode : public cmGeneratorExpressionNode
 {
   Angle_RNode() {}
 
-  virtual int NumExpectedParameters() const { return 0; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 0; }
 
   std::string Evaluate(const std::vector<std::string>&,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return ">";
   }
@@ -296,12 +296,12 @@ static const struct CommaNode : public cmGeneratorExpressionNode
 {
   CommaNode() {}
 
-  virtual int NumExpectedParameters() const { return 0; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 0; }
 
   std::string Evaluate(const std::vector<std::string>&,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return ",";
   }
@@ -311,12 +311,12 @@ static const struct SemicolonNode : public cmGeneratorExpressionNode
 {
   SemicolonNode() {}
 
-  virtual int NumExpectedParameters() const { return 0; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 0; }
 
   std::string Evaluate(const std::vector<std::string>&,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return ";";
   }
@@ -326,7 +326,7 @@ struct CompilerIdNode : public cmGeneratorExpressionNode
 {
   CompilerIdNode() {}
 
-  virtual int NumExpectedParameters() const { return OneOrZeroParameters; }
+  int NumExpectedParameters() const CM_OVERRIDE { return OneOrZeroParameters; }
 
   std::string EvaluateWithLanguage(const std::vector<std::string>& parameters,
                                    cmGeneratorExpressionContext* context,
@@ -381,6 +381,7 @@ static const struct CCompilerIdNode : public CompilerIdNode
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagChecker) const
+    CM_OVERRIDE
   {
     if (!context->HeadTarget) {
       reportError(
@@ -402,6 +403,7 @@ static const struct CXXCompilerIdNode : public CompilerIdNode
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagChecker) const
+    CM_OVERRIDE
   {
     if (!context->HeadTarget) {
       reportError(
@@ -419,7 +421,7 @@ struct CompilerVersionNode : public cmGeneratorExpressionNode
 {
   CompilerVersionNode() {}
 
-  virtual int NumExpectedParameters() const { return OneOrZeroParameters; }
+  int NumExpectedParameters() const CM_OVERRIDE { return OneOrZeroParameters; }
 
   std::string EvaluateWithLanguage(const std::vector<std::string>& parameters,
                                    cmGeneratorExpressionContext* context,
@@ -460,6 +462,7 @@ static const struct CCompilerVersionNode : public CompilerVersionNode
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagChecker) const
+    CM_OVERRIDE
   {
     if (!context->HeadTarget) {
       reportError(
@@ -481,6 +484,7 @@ static const struct CxxCompilerVersionNode : public CompilerVersionNode
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagChecker) const
+    CM_OVERRIDE
   {
     if (!context->HeadTarget) {
       reportError(
@@ -498,12 +502,12 @@ struct PlatformIdNode : public cmGeneratorExpressionNode
 {
   PlatformIdNode() {}
 
-  virtual int NumExpectedParameters() const { return OneOrZeroParameters; }
+  int NumExpectedParameters() const CM_OVERRIDE { return OneOrZeroParameters; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     const char* platformId =
       context->LG->GetMakefile()->GetSafeDefinition("CMAKE_SYSTEM_NAME");
@@ -526,12 +530,12 @@ static const struct VersionGreaterNode : public cmGeneratorExpressionNode
 {
   VersionGreaterNode() {}
 
-  virtual int NumExpectedParameters() const { return 2; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 2; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return cmSystemTools::VersionCompare(cmSystemTools::OP_GREATER,
                                          parameters.front().c_str(),
@@ -545,12 +549,12 @@ static const struct VersionLessNode : public cmGeneratorExpressionNode
 {
   VersionLessNode() {}
 
-  virtual int NumExpectedParameters() const { return 2; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 2; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return cmSystemTools::VersionCompare(cmSystemTools::OP_LESS,
                                          parameters.front().c_str(),
@@ -564,12 +568,12 @@ static const struct VersionEqualNode : public cmGeneratorExpressionNode
 {
   VersionEqualNode() {}
 
-  virtual int NumExpectedParameters() const { return 2; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 2; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return cmSystemTools::VersionCompare(cmSystemTools::OP_EQUAL,
                                          parameters.front().c_str(),
@@ -583,10 +587,10 @@ static const struct LinkOnlyNode : public cmGeneratorExpressionNode
 {
   LinkOnlyNode() {}
 
-  std::string Evaluate(const std::vector<std::string>& parameters,
-                       cmGeneratorExpressionContext*,
-                       const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker* dagChecker) const
+  std::string Evaluate(
+    const std::vector<std::string>& parameters, cmGeneratorExpressionContext*,
+    const GeneratorExpressionContent*,
+    cmGeneratorExpressionDAGChecker* dagChecker) const CM_OVERRIDE
   {
     if (!dagChecker->GetTransitivePropertiesOnly()) {
       return parameters.front();
@@ -599,12 +603,12 @@ static const struct ConfigurationNode : public cmGeneratorExpressionNode
 {
   ConfigurationNode() {}
 
-  virtual int NumExpectedParameters() const { return 0; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 0; }
 
   std::string Evaluate(const std::vector<std::string>&,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     context->HadContextSensitiveCondition = true;
     return context->Config;
@@ -615,12 +619,12 @@ static const struct ConfigurationTestNode : public cmGeneratorExpressionNode
 {
   ConfigurationTestNode() {}
 
-  virtual int NumExpectedParameters() const { return OneOrZeroParameters; }
+  int NumExpectedParameters() const CM_OVERRIDE { return OneOrZeroParameters; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     if (parameters.empty()) {
       return configurationNode.Evaluate(parameters, context, content, 0);
@@ -673,14 +677,14 @@ static const struct JoinNode : public cmGeneratorExpressionNode
 {
   JoinNode() {}
 
-  virtual int NumExpectedParameters() const { return 2; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 2; }
 
-  virtual bool AcceptsArbitraryContentParameter() const { return true; }
+  bool AcceptsArbitraryContentParameter() const CM_OVERRIDE { return true; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     std::vector<std::string> list;
     cmSystemTools::ExpandListArgument(parameters.front(), list);
@@ -692,12 +696,13 @@ static const struct CompileLanguageNode : public cmGeneratorExpressionNode
 {
   CompileLanguageNode() {}
 
-  virtual int NumExpectedParameters() const { return OneOrZeroParameters; }
+  int NumExpectedParameters() const CM_OVERRIDE { return OneOrZeroParameters; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagChecker) const
+    CM_OVERRIDE
   {
     if (context->Language.empty()) {
       reportError(
@@ -795,12 +800,13 @@ static const struct TargetPropertyNode : public cmGeneratorExpressionNode
   TargetPropertyNode() {}
 
   // This node handles errors on parameter count itself.
-  virtual int NumExpectedParameters() const { return OneOrMoreParameters; }
+  int NumExpectedParameters() const CM_OVERRIDE { return OneOrMoreParameters; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagCheckerParent) const
+    CM_OVERRIDE
   {
     if (parameters.size() != 1 && parameters.size() != 2) {
       reportError(
@@ -1087,20 +1093,20 @@ static const struct TargetNameNode : public cmGeneratorExpressionNode
 {
   TargetNameNode() {}
 
-  virtual bool GeneratesContent() const { return true; }
+  bool GeneratesContent() const CM_OVERRIDE { return true; }
 
-  virtual bool AcceptsArbitraryContentParameter() const { return true; }
-  virtual bool RequiresLiteralInput() const { return true; }
+  bool AcceptsArbitraryContentParameter() const CM_OVERRIDE { return true; }
+  bool RequiresLiteralInput() const CM_OVERRIDE { return true; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext*,
                        const GeneratorExpressionContent*,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     return parameters.front();
   }
 
-  virtual int NumExpectedParameters() const { return 1; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 1; }
 
 } targetNameNode;
 
@@ -1111,7 +1117,7 @@ static const struct TargetObjectsNode : public cmGeneratorExpressionNode
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     if (!context->EvaluateForBuildsystem) {
       std::ostringstream e;
@@ -1179,12 +1185,13 @@ static const struct CompileFeaturesNode : public cmGeneratorExpressionNode
 {
   CompileFeaturesNode() {}
 
-  virtual int NumExpectedParameters() const { return OneOrMoreParameters; }
+  int NumExpectedParameters() const CM_OVERRIDE { return OneOrMoreParameters; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagChecker) const
+    CM_OVERRIDE
   {
     cmGeneratorTarget const* target = context->HeadTarget;
     if (!target) {
@@ -1306,12 +1313,12 @@ static const struct TargetPolicyNode : public cmGeneratorExpressionNode
 {
   TargetPolicyNode() {}
 
-  virtual int NumExpectedParameters() const { return 1; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 1; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     if (!context->HeadTarget) {
       reportError(
@@ -1365,13 +1372,13 @@ static const struct InstallPrefixNode : public cmGeneratorExpressionNode
 {
   InstallPrefixNode() {}
 
-  virtual bool GeneratesContent() const { return true; }
-  virtual int NumExpectedParameters() const { return 0; }
+  bool GeneratesContent() const CM_OVERRIDE { return true; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 0; }
 
   std::string Evaluate(const std::vector<std::string>&,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     reportError(context, content->GetOriginalExpression(),
                 "INSTALL_PREFIX is a marker for install(EXPORT) only.  It "
@@ -1529,12 +1536,13 @@ struct TargetFilesystemArtifact : public cmGeneratorExpressionNode
 {
   TargetFilesystemArtifact() {}
 
-  virtual int NumExpectedParameters() const { return 1; }
+  int NumExpectedParameters() const CM_OVERRIDE { return 1; }
 
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
                        cmGeneratorExpressionDAGChecker* dagChecker) const
+    CM_OVERRIDE
   {
     // Lookup the referenced target.
     std::string name = *parameters.begin();
@@ -1606,7 +1614,7 @@ static const struct ShellPathNode : public cmGeneratorExpressionNode
   std::string Evaluate(const std::vector<std::string>& parameters,
                        cmGeneratorExpressionContext* context,
                        const GeneratorExpressionContent* content,
-                       cmGeneratorExpressionDAGChecker*) const
+                       cmGeneratorExpressionDAGChecker*) const CM_OVERRIDE
   {
     if (!cmSystemTools::FileIsFullPath(parameters.front())) {
       reportError(context, content->GetOriginalExpression(),
diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 9a025d911..3668c8297 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -27,7 +27,10 @@
 #include "assert.h"
 #include <errno.h>
 
-#if defined(CMAKE_BUILD_WITH_CMAKE)
+#if defined(CMake_HAVE_CXX_UNORDERED_SET)
+#include <unordered_set>
+#define UNORDERED_SET std::unordered_set
+#elif defined(CMAKE_BUILD_WITH_CMAKE)
 #include <cmsys/hash_set.hxx>
 #define UNORDERED_SET cmsys::hash_set
 #else
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 68ff042ad..789e51526 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -25,7 +25,7 @@
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #include "cmFileLockPool.h"
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -433,7 +433,7 @@ protected:
 
 private:
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, cmTarget*> TargetMap;
   typedef std::unordered_map<std::string, cmGeneratorTarget*>
     GeneratorTargetMap;
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 1680c6aaf..c68cd1c87 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -31,7 +31,7 @@
 #include <cmsys/RegularExpression.hxx>
 #include <cmsys/auto_ptr.hxx>
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -796,7 +796,7 @@ protected:
   // libraries, classes, and executables
   mutable cmTargets Targets;
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, cmTarget*> TargetMap;
 #else
   typedef cmsys::hash_map<std::string, cmTarget*> TargetMap;
@@ -915,7 +915,7 @@ private:
 
 // A map for fast output to input look up.
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, cmSourceFile*> OutputToSourceMap;
 #else
   typedef cmsys::hash_map<std::string, cmSourceFile*> OutputToSourceMap;
diff --git a/Source/cmOrderDirectories.cxx b/Source/cmOrderDirectories.cxx
index 00606c796..20f224610 100644
--- a/Source/cmOrderDirectories.cxx
+++ b/Source/cmOrderDirectories.cxx
@@ -157,7 +157,7 @@ public:
     }
   }
 
-  virtual void Report(std::ostream& e)
+  void Report(std::ostream& e) CM_OVERRIDE
   {
     e << "runtime library [";
     if (this->SOName.empty()) {
@@ -168,7 +168,7 @@ public:
     e << "]";
   }
 
-  virtual bool FindConflict(std::string const& dir);
+  bool FindConflict(std::string const& dir) CM_OVERRIDE;
 
 private:
   // The soname of the shared library if it is known.
@@ -212,12 +212,12 @@ public:
   {
   }
 
-  virtual void Report(std::ostream& e)
+  void Report(std::ostream& e) CM_OVERRIDE
   {
     e << "link library [" << this->FileName << "]";
   }
 
-  virtual bool FindConflict(std::string const& dir);
+  bool FindConflict(std::string const& dir) CM_OVERRIDE;
 };
 
 bool cmOrderDirectoriesConstraintLibrary::FindConflict(std::string const& dir)
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 43860802c..5e5ed2b29 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -27,7 +27,11 @@
 #include <map>
 #include <set>
 #include <stdlib.h> // required for atof
-#if defined(CMAKE_BUILD_WITH_CMAKE)
+
+#if defined(CMake_HAVE_CXX_UNORDERED_SET)
+#include <unordered_set>
+#define UNORDERED_SET std::unordered_set
+#elif defined(CMAKE_BUILD_WITH_CMAKE)
 #include <cmsys/hash_set.hxx>
 #define UNORDERED_SET cmsys::hash_set
 #else
diff --git a/Source/cmTarget.h b/Source/cmTarget.h
index f91e5c68d..9e095c2de 100644
--- a/Source/cmTarget.h
+++ b/Source/cmTarget.h
@@ -21,7 +21,7 @@
 
 #include <cmsys/auto_ptr.hxx>
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -331,7 +331,7 @@ private:
 };
 
 #ifdef CMAKE_BUILD_WITH_CMAKE
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 typedef std::unordered_map<std::string, cmTarget> cmTargets;
 #else
 typedef cmsys::hash_map<std::string, cmTarget> cmTargets;
diff --git a/bootstrap b/bootstrap
index 27cf9d861..a9f340226 100755
--- a/bootstrap
+++ b/bootstrap
@@ -1272,6 +1272,7 @@ cmake_report cmConfigure.h${_tmp} "#define CMAKE_BOOTSTRAP_BINARY_DIR \"${CMAKE_
 cmake_report cmConfigure.h${_tmp} "#define CMAKE_BIN_DIR \"/bootstrap-not-insalled\""
 cmake_report cmConfigure.h${_tmp} "#define CMAKE_DATA_DIR \"/bootstrap-not-insalled\""
 cmake_report cmConfigure.h${_tmp} "#define CMAKE_BOOTSTRAP"
+cmake_report cmConfigure.h${_tmp} "#define CM_OVERRIDE"
 
 # Regenerate configured headers
 for h in Configure VersionConfig; do