diff --git a/clang/include/clang/Basic/OpenCLOptions.h b/clang/include/clang/Basic/OpenCLOptions.h
--- a/clang/include/clang/Basic/OpenCLOptions.h
+++ b/clang/include/clang/Basic/OpenCLOptions.h
@@ -37,33 +37,46 @@
   }
 
   bool isEnabled(llvm::StringRef Ext) const {
-    return OptMap.find(Ext)->second.Enabled;
+    auto E = OptMap.find(Ext);
+    return E != OptMap.end() && E->second.Enabled;
   }
 
   // Is supported as either an extension or an (optional) core feature for
   // OpenCL version \p CLVer.
   bool isSupported(llvm::StringRef Ext, const LangOptions &LO) const {
+    auto E = OptMap.find(Ext);
+    if (E == OptMap.end()) {
+      return false;
+    }
     // In C++ mode all extensions should work at least as in v2.0.
     auto CLVer = LO.OpenCLCPlusPlus ? 200 : LO.OpenCLVersion;
-    auto I = OptMap.find(Ext)->getValue();
+    auto I = E->getValue();
     return I.Supported && I.Avail <= CLVer;
   }
 
   // Is supported (optional) OpenCL core features for OpenCL version \p CLVer.
   // For supported extension, return false.
   bool isSupportedCore(llvm::StringRef Ext, const LangOptions &LO) const {
+    auto E = OptMap.find(Ext);
+    if (E == OptMap.end()) {
+      return false;
+    }
     // In C++ mode all extensions should work at least as in v2.0.
     auto CLVer = LO.OpenCLCPlusPlus ? 200 : LO.OpenCLVersion;
-    auto I = OptMap.find(Ext)->getValue();
+    auto I = E->getValue();
     return I.Supported && I.Avail <= CLVer && I.Core != ~0U && CLVer >= I.Core;
   }
 
   // Is supported OpenCL extension for OpenCL version \p CLVer.
   // For supported (optional) core feature, return false.
   bool isSupportedExtension(llvm::StringRef Ext, const LangOptions &LO) const {
+    auto E = OptMap.find(Ext);
+    if (E == OptMap.end()) {
+      return false;
+    }
     // In C++ mode all extensions should work at least as in v2.0.
     auto CLVer = LO.OpenCLCPlusPlus ? 200 : LO.OpenCLVersion;
-    auto I = OptMap.find(Ext)->getValue();
+    auto I = E->getValue();
     return I.Supported && I.Avail <= CLVer && (I.Core == ~0U || CLVer < I.Core);
   }