diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f8a7a12451d..bf0dbe0fb16 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2019-08-18  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* config/rs6000/darwin.h (TARGET_OS_CPP_BUILTINS): Add asserts
+	for cpu and machine.  Factor 64/32b builtins.
+
 2019-08-18  Gerald Pfeifer  <gerald@pfeifer.com>
 
 	* doc/install.texi (Specific, bfin): blackfin.uclinux.org is
diff --git a/gcc/config/rs6000/darwin.h b/gcc/config/rs6000/darwin.h
index 150dc4f4cdd..a626325c2d0 100644
--- a/gcc/config/rs6000/darwin.h
+++ b/gcc/config/rs6000/darwin.h
@@ -52,11 +52,23 @@
 #define TARGET_OS_CPP_BUILTINS()			\
   do							\
     {							\
-      if (!TARGET_64BIT) builtin_define ("__ppc__");	\
-      if (!TARGET_64BIT) builtin_define ("__PPC__");	\
-      if (TARGET_64BIT) builtin_define ("__ppc64__");	\
-      if (TARGET_64BIT) builtin_define ("__PPC64__");	\
       builtin_define ("__POWERPC__");			\
+      builtin_define ("__PPC__");			\
+      if (TARGET_64BIT)					\
+	{						\
+	  builtin_define ("__ppc64__");			\
+	  builtin_define ("__PPC64__");			\
+	  builtin_define ("__powerpc64__");		\
+	  builtin_assert ("cpu=powerpc64");		\
+	  builtin_assert ("machine=powerpc64");		\
+	}						\
+      else						\
+	{						\
+	  builtin_define ("__ppc__");			\
+	  builtin_define_std ("PPC");			\
+	  builtin_assert ("cpu=powerpc");		\
+	  builtin_assert ("machine=powerpc");		\
+	}						\
       builtin_define ("__NATURAL_ALIGNMENT__");		\
       darwin_cpp_builtins (pfile);			\
     }							\