diff --git a/clang/lib/Basic/Targets/PPC.cpp b/clang/lib/Basic/Targets/PPC.cpp
--- a/clang/lib/Basic/Targets/PPC.cpp
+++ b/clang/lib/Basic/Targets/PPC.cpp
@@ -264,6 +264,9 @@
   }
   if (getTriple().isOSAIX()) {
     Builder.defineMacro("__THW_PPC__");
+    // Define __PPC and __powerpc for AIX XL C/C++ compatibility
+    Builder.defineMacro("__PPC");
+    Builder.defineMacro("__powerpc");
   }
 
   // Target properties.
diff --git a/clang/test/Preprocessor/init-ppc.c b/clang/test/Preprocessor/init-ppc.c
--- a/clang/test/Preprocessor/init-ppc.c
+++ b/clang/test/Preprocessor/init-ppc.c
@@ -517,6 +517,7 @@
 // PPC-AIX-NOT:#define __NATURAL_ALIGNMENT__ 1
 // PPC-AIX:#define __POINTER_WIDTH__ 32
 // PPC-AIX:#define __POWERPC__ 1
+// PPC-AIX:#define __PPC 1
 // PPC-AIX:#define __PPC__ 1
 // PPC-AIX:#define __PTRDIFF_TYPE__ long int
 // PPC-AIX:#define __PTRDIFF_WIDTH__ 32
@@ -584,6 +585,7 @@
 // PPC-AIX:#define __WCHAR_WIDTH__ 16
 // PPC-AIX:#define __WINT_TYPE__ int
 // PPC-AIX:#define __WINT_WIDTH__ 32
+// PPC-AIX:#define __powerpc 1
 // PPC-AIX:#define __powerpc__ 1
 // PPC-AIX:#define __ppc__ 1