diff --git a/config/ChangeLog b/config/ChangeLog
index c90079c72..800698cf2 100644
--- a/config/ChangeLog
+++ b/config/ChangeLog
@@ -1,3 +1,8 @@
+2005-09-23  Tom Tromey  <tromey@redhat.com>
+
+	* enable.m4: New file.
+	* tls.m4: New file.
+
 2005-08-12  Paolo Bonzini  <bonzini@gnu.org>
 
 	* config/acx.m4 (NCN_CHECK_TARGET_TOOL, NCN_STRICT_CHECK_TOOL,
diff --git a/config/enable.m4 b/config/enable.m4
new file mode 100644
index 000000000..88b29b8aa
--- /dev/null
+++ b/config/enable.m4
@@ -0,0 +1,38 @@
+dnl ----------------------------------------------------------------------
+dnl This whole bit snagged from libstdc++-v3.
+
+dnl
+dnl GCC_ENABLE
+dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING)
+dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, permit a|b|c)
+dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, SHELL-CODE-HANDLER)
+dnl
+dnl See docs/html/17_intro/configury.html#enable for documentation.
+dnl
+AC_DEFUN([GCC_ENABLE],[dnl
+m4_define([_g_switch],[--enable-$1])dnl
+m4_define([_g_help],[AC_HELP_STRING(_g_switch$3,[$4 @<:@default=$2@:>@])])dnl
+ AC_ARG_ENABLE($1,_g_help,
+  m4_bmatch([$5],
+   [^permit ],
+     [[
+      case "$enableval" in
+       m4_bpatsubst([$5],[permit ])) ;;
+       *) AC_MSG_ERROR(Unknown argument to enable/disable $1) ;;
+          dnl Idea for future:  generate a URL pointing to
+          dnl "onlinedocs/configopts.html#whatever"
+      esac
+     ]],
+   [^$],
+     [[
+      case "$enableval" in
+       yes|no) ;;
+       *) AC_MSG_ERROR(Argument to enable/disable $1 must be yes or no) ;;
+      esac
+     ]],
+   [[$5]]),
+  [enable_]m4_bpatsubst([$1],-,_)[=][$2])
+m4_undefine([_g_switch])dnl
+m4_undefine([_g_help])dnl
+])
+
diff --git a/config/tls.m4 b/config/tls.m4
new file mode 100644
index 000000000..5cbb6854f
--- /dev/null
+++ b/config/tls.m4
@@ -0,0 +1,21 @@
+dnl Check whether the target supports TLS.
+AC_DEFUN([GCC_CHECK_TLS], [
+  GCC_ENABLE(tls, yes, [Use thread-local storage])
+  AC_CACHE_CHECK([whether the target supports thread-local storage],
+		 have_tls, [
+    AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+      [dnl If the test case passed with dynamic linking, try again with
+      dnl static linking.  This fails at least with some older Red Hat
+      dnl releases.
+      save_LDFLAGS="$LDFLAGS"
+      LDFLAGS="-static $LDFLAGS"
+      AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+		    [have_tls=yes], [have_tls=no], [])
+      LDFLAGS="$save_LDFLAGS"],
+      [have_tls=no],
+      [AC_COMPILE_IFELSE([__thread int foo;], [have_tls=yes], [have_tls=no])]
+    )])
+  if test "$enable_tls $have_tls" = "yes yes"; then
+    AC_DEFINE(HAVE_TLS, 1,
+	      [Define to 1 if the target supports thread-local storage.])
+  fi])