diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index 7f2b592f3..2c3834a0e 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -616,6 +616,9 @@ cmGlobalGenerator::EnableLanguage(std::vector<std::string>const& languages,
       {
       this->LanguageToOriginalSharedLibFlags[lang] = sharedLibFlags;
       }
+
+    // Translate compiler ids for compatibility.
+    this->CheckCompilerIdCompatibility(mf, lang);
     } // end for each language
 
   // Now load files that can override any settings on the platform or for
@@ -631,6 +634,44 @@ cmGlobalGenerator::EnableLanguage(std::vector<std::string>const& languages,
     }
 }
 
+//----------------------------------------------------------------------------
+void cmGlobalGenerator::CheckCompilerIdCompatibility(cmMakefile* mf,
+                                                     std::string lang)
+{
+  std::string compilerIdVar = "CMAKE_" + lang + "_COMPILER_ID";
+  const char* compilerId = mf->GetDefinition(compilerIdVar.c_str());
+  if(compilerId && strcmp(compilerId, "AppleClang") == 0)
+    {
+    cmPolicies* policies = this->CMakeInstance->GetPolicies();
+    switch(mf->GetPolicyStatus(cmPolicies::CMP0025))
+      {
+      case cmPolicies::WARN:
+        if(!this->CMakeInstance->GetIsInTryCompile())
+          {
+          cmOStringStream w;
+          w << policies->GetPolicyWarning(cmPolicies::CMP0025) << "\n"
+            "Converting " << lang <<
+            " compiler id \"AppleClang\" to \"Clang\" for compatibility."
+            ;
+          mf->IssueMessage(cmake::AUTHOR_WARNING, w.str());
+          }
+      case cmPolicies::OLD:
+        // OLD behavior is to convert AppleClang to Clang.
+        mf->AddDefinition(compilerIdVar.c_str(), "Clang");
+        break;
+      case cmPolicies::REQUIRED_IF_USED:
+      case cmPolicies::REQUIRED_ALWAYS:
+        mf->IssueMessage(
+          cmake::FATAL_ERROR,
+          policies->GetRequiredPolicyError(cmPolicies::CMP0025)
+          );
+      case cmPolicies::NEW:
+        // NEW behavior is to keep AppleClang.
+        break;
+      }
+    }
+}
+
 //----------------------------------------------------------------------------
 const char*
 cmGlobalGenerator::GetLanguageOutputExtension(cmSourceFile const& source)
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 18aba24bf..70f6e32b2 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -383,6 +383,8 @@ private:
   void WriteSummary();
   void WriteSummary(cmTarget* target);
 
+  void CheckCompilerIdCompatibility(cmMakefile* mf, std::string lang);
+
   cmExternalMakefileProjectGenerator* ExtraGenerator;
 
   // track files replaced during a Generate
diff --git a/Source/cmPolicies.cxx b/Source/cmPolicies.cxx
index 45670b3ca..c3d6a946e 100644
--- a/Source/cmPolicies.cxx
+++ b/Source/cmPolicies.cxx
@@ -620,6 +620,23 @@ cmPolicies::cmPolicies()
     "The NEW behavior for this policy is to not to allow including the "
     "result of an export() command.",
     2,8,13,0, cmPolicies::WARN);
+
+  this->DefinePolicy(
+    CMP0025, "CMP0025",
+    "Compiler id for Apple Clang is now AppleClang.",
+    "CMake >= 2.8.13 recognize that Apple Clang is a different compiler "
+    "than upstream Clang and that they have different version numbers.  "
+    "CMake now prefers to present this to projects by setting "
+    "CMAKE_<LANG>_COMPILER_ID to \"AppleClang\" instead of \"Clang\".  "
+    "However, existing projects may assume the compiler id for Apple Clang "
+    "is just \"Clang\" as it was in CMake < 2.8.13.  "
+    "Therefore this policy determines for Apple Clang which compiler id "
+    "to report in CMAKE_<LANG>_COMPILER_ID after <LANG> is enabled by "
+    "the project() or enable_language() command."
+    "\n"
+    "The OLD behavior for this policy is to use compiler id \"Clang\".  "
+    "The NEW behavior for this policy is to use compiler id \"AppleClang\".",
+    2,8,13,0, cmPolicies::WARN);
 }
 
 cmPolicies::~cmPolicies()
diff --git a/Source/cmPolicies.h b/Source/cmPolicies.h
index bafe5b2d3..ec8959d45 100644
--- a/Source/cmPolicies.h
+++ b/Source/cmPolicies.h
@@ -75,6 +75,7 @@ public:
     CMP0022, ///< INTERFACE_LINK_LIBRARIES defines the link interface
     CMP0023, ///< Disallow mixing keyword and plain tll signatures
     CMP0024, ///< Disallow including export() result.
+    CMP0025, ///< Compiler id for Apple Clang is now AppleClang
 
     /** \brief Always the last entry.
      *