diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 866c8b25d72..061d63e1bfd 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2005-05-16  Richard Sandiford  <rsandifo@redhat.com>
+
+	* Makefile.in (options.c): Tell optc-gen.awk to include config.h,
+	system.h, coretypes.h and tm.h.
+	(options.o): Update dependencies accordingly.
+	* optc-gen.awk: Allow header_name to be a list of filenames.
+	Handle the "Condition" flag.
+	* opts.h (CL_DISABLED): New flag.
+	* opts.c (handle_option): Print an error for CL_DISABLED options.
+	* doc/options.texi: Document the "Condition" option flag.
+
 2005-05-16  Paolo Bonzini  <bonzini@gnu.org>
 
 	* tree-inline.c (estimate_num_insns_1): Handle VEC_COND_EXPR.
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 517d5d8b2ca..8d0d15ca798 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1569,7 +1569,7 @@ s-options: $(ALL_OPT_FILES) Makefile $(srcdir)/opt-gather.awk
 
 options.c: optionlist $(srcdir)/opt-functions.awk $(srcdir)/optc-gen.awk
 	$(AWK) -f $(srcdir)/opt-functions.awk -f $(srcdir)/optc-gen.awk \
-	       -v header_name="options.h" < $< > $@ 
+	       -v header_name="config.h system.h coretypes.h tm.h" < $< > $@ 
 
 options.h: s-options-h ; @true
 s-options-h: optionlist $(srcdir)/opt-functions.awk $(srcdir)/opth-gen.awk
@@ -1578,7 +1578,7 @@ s-options-h: optionlist $(srcdir)/opt-functions.awk $(srcdir)/opth-gen.awk
 	$(SHELL) $(srcdir)/../move-if-change tmp-options.h options.h
 	$(STAMP) $@
 
-options.o: options.c options.h opts.h intl.h
+options.o: options.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) opts.h intl.h
 
 dumpvers: dumpvers.c
 
diff --git a/gcc/doc/options.texi b/gcc/doc/options.texi
index 2ab189317da..307a325e5de 100644
--- a/gcc/doc/options.texi
+++ b/gcc/doc/options.texi
@@ -191,4 +191,11 @@ The state of the option should be printed by @option{-fverbose-asm}.
 @item Undocumented
 The option is deliberately missing documentation and should not
 be included in the @option{--help} output.
+
+@item Condition(@var{cond})
+The option should only be accepted if preprocessor condition
+@var{cond} is true.  Note that any C declarations associated with the
+option will be present even if @var{cond} is false; @var{cond} simply
+controls whether the option is accepted and whether it is printed in
+the @option{--help} output.
 @end table
diff --git a/gcc/optc-gen.awk b/gcc/optc-gen.awk
index 5476674a163..e647cd9ad21 100644
--- a/gcc/optc-gen.awk
+++ b/gcc/optc-gen.awk
@@ -57,7 +57,9 @@ END {
 print "/* This file is auto-generated by opts.sh.  */"
 print ""
 print "#include <intl.h>"
-print "#include " quote header_name quote
+n_headers = split(header_name, headers, " ")
+for (i = 1; i <= n_headers; i++)
+	print "#include " quote headers[i] quote
 print "#include " quote "opts.h" quote
 print ""
 
@@ -135,10 +137,20 @@ for (i = 0; i < n_opts; i++) {
 	else
 		hlp = quote help[i] quote;
 
-	printf("  { %c-%s%c,\n    %s,\n    %s, %u, %s, %s, %s }%s\n",
-		quote, opts[i], quote, hlp, back_chain[i], len,
-		switch_flags(flags[i]),
-		var_ref(flags[i]), var_set(flags[i]), comma)
+	printf("  { %c-%s%c,\n    %s,\n    %s, %u,\n",
+	       quote, opts[i], quote, hlp, back_chain[i], len)
+	condition = opt_args("Condition", flags[i])
+	cl_flags = switch_flags(flags[i])
+	if (condition != "")
+		printf("#if %s\n" \
+		       "    %s,\n" \
+		       "#else\n" \
+		       "    CL_DISABLED,\n" \
+		       "#endif\n",
+		       condition, cl_flags, cl_flags)
+	else
+		printf("    %s,\n", cl_flags)
+	printf("    %s, %s }%s\n", var_ref(flags[i]), var_set(flags[i]), comma)
 }
 
 print "};"
diff --git a/gcc/opts.c b/gcc/opts.c
index 97f89314fb1..896728c3727 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -315,6 +315,14 @@ handle_option (const char **argv, unsigned int lang_mask)
   /* We've recognized this switch.  */
   result = 1;
 
+  /* Check to see if the option is disabled for this configuration.  */
+  if (option->flags & CL_DISABLED)
+    {
+      error ("command line option %qs"
+	     " is not supported by this configuration", opt);
+      goto done;
+    }
+
   /* Sort out any argument the switch takes.  */
   if (option->flags & CL_JOINED)
     {
diff --git a/gcc/opts.h b/gcc/opts.h
index bed419e820d..758f8309abd 100644
--- a/gcc/opts.h
+++ b/gcc/opts.h
@@ -52,6 +52,7 @@ extern const struct cl_option cl_options[];
 extern const unsigned int cl_options_count;
 extern const char *const lang_names[];
 
+#define CL_DISABLED		(1 << 21) /* Disabled in this configuration.  */
 #define CL_TARGET		(1 << 22) /* Target-specific option.  */
 #define CL_REPORT		(1 << 23) /* Report argument with -fverbose-asm  */
 #define CL_JOINED		(1 << 24) /* If takes joined argument.  */