diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index cba3e3a..bd1a883 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -194,6 +194,13 @@
     Builder.defineMacro("__LP64__");
   }
 
+  std::string CodeModel = getTargetOpts().CodeModel;
+  if (CodeModel == "default")
+    CodeModel = "small";
+  for (char &c : CodeModel)
+    c = toupper(c);
+  Builder.defineMacro("__AARCH64_CMODEL_" + CodeModel + "__");
+
   // ACLE predefines. Many can only have one possible value on v8 AArch64.
   Builder.defineMacro("__ARM_ACLE", "200");
   Builder.defineMacro("__ARM_ARCH", "8");