/* Pass -d* flags, possibly modifying -dumpdir, -dumpbase et al.
+@@ -1265,7 +1270,11 @@ static const char *cc1_options =
+ %{coverage:-fprofile-arcs -ftest-coverage}\
+ %{fprofile-arcs|fprofile-generate*|coverage:\
+ %{!fprofile-update=single:\
+- %{pthread:-fprofile-update=prefer-atomic}}}";
++ %{pthread:-fprofile-update=prefer-atomic}}}"
++#ifdef POISON_BY_DEFAULT
++ " -Werror=poison-system-directories"
++#endif
++ ;
+
+ static const char *asm_options =
+ "%{-target-help:%:print-asm-header()} "
diff --git a/gcc/incpath.cc b/gcc/incpath.cc
index bd2a97938eb..c80f100f476 100644
--- a/gcc/incpath.cc