diff --git a/gcc/gcc/config/m68k/m68k-macos.h b/gcc/gcc/config/m68k/m68k-macos.h
index d43ef14d44..b1ee725bb6 100644
--- a/gcc/gcc/config/m68k/m68k-macos.h
+++ b/gcc/gcc/config/m68k/m68k-macos.h
@@ -16,3 +16,11 @@
 #undef CPP_SPEC
 #define CPP_SPEC "-Wno-trigraphs"
 
+#undef TARGET_OS_CPP_BUILTINS
+#define TARGET_OS_CPP_BUILTINS()          \
+  do                                      \
+    {                                     \
+      builtin_define ("macintosh");       \
+      builtin_define ("Macintosh");       \
+    }                                     \
+  while (0)
diff --git a/gcc/gcc/config/rs6000/macos.h b/gcc/gcc/config/rs6000/macos.h
index 97a30e1dd6..b8af463686 100644
--- a/gcc/gcc/config/rs6000/macos.h
+++ b/gcc/gcc/config/rs6000/macos.h
@@ -152,6 +152,8 @@
       builtin_define ("__PPC__");               \
       builtin_define ("__POWERPC__");           \
       builtin_define ("__NATURAL_ALIGNMENT__"); \
+      builtin_define ("macintosh");             \
+      builtin_define ("Macintosh");             \
       builtin_assert ("system=macos");     \
       builtin_assert ("cpu=powerpc");     \
       builtin_assert ("machine=powerpc"); \