diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 1741755..1c7793e 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -408,6 +408,39 @@
   if (LangOpts.ObjC1)
     Builder.defineMacro("__OBJC__");
 
+  // OpenCL v1.0/1.1 s6.9, v1.2/2.0 s6.10: Preprocessor Directives and Macros.
+  if (LangOpts.OpenCL) {
+    // OpenCL v1.0 and v1.1 do not have a predefined macro to indicate the
+    // language standard with which the program is compiled. __OPENCL_VERSION__
+    // is for the OpenCL version supported by the OpenCL device, which is not
+    // necessarily the language standard with which the program is compiled.
+    // A shared OpenCL header file requires a macro to indicate the language
+    // standard. As a workaround, __OPENCL_C_VERSION__ is defined for
+    // OpenCL v1.0 and v1.1.
+    switch (LangOpts.OpenCLVersion) {
+    case 100:
+      Builder.defineMacro("__OPENCL_C_VERSION__", "100");
+      break;
+    case 110:
+      Builder.defineMacro("__OPENCL_C_VERSION__", "110");
+      break;
+    case 120:
+      Builder.defineMacro("__OPENCL_C_VERSION__", "120");
+      break;
+    case 200:
+      Builder.defineMacro("__OPENCL_C_VERSION__", "200");
+      break;
+    default:
+      llvm_unreachable("Unsupported OpenCL version");
+    }
+    Builder.defineMacro("CL_VERSION_1_0", "100");
+    Builder.defineMacro("CL_VERSION_1_1", "110");
+    Builder.defineMacro("CL_VERSION_1_2", "120");
+    Builder.defineMacro("CL_VERSION_2_0", "200");
+
+    if (LangOpts.FastRelaxedMath)
+      Builder.defineMacro("__FAST_RELAXED_MATH__");
+  }
   // Not "standard" per se, but available even with the -undef flag.
   if (LangOpts.AsmPreprocessor)
     Builder.defineMacro("__ASSEMBLER__");