--- a/lto-plugin/configure.ac	Sun Aug 21 07:07:55 2011 +0900
+++ b/lto-plugin/configure.ac	Fri Oct 27 22:46:09 2017 +0900
@@ -4,8 +4,50 @@
 GCC_TOPLEV_SUBDIRS
 AM_INIT_AUTOMAKE([foreign no-dist])
 AM_MAINTAINER_MODE
+AC_ARG_WITH(libiberty,
+  [AS_HELP_STRING([--with-libiberty=PATH],
+    [specify the directory where to find libiberty [../libiberty]])],
+  [], with_libiberty=../libiberty)
+AC_SUBST(with_libiberty)
+AC_USE_SYSTEM_EXTENSIONS
 AC_PROG_CC
 AC_SYS_LARGEFILE
+ACX_PROG_CC_WARNING_OPTS([-Wall], [ac_lto_plugin_warn_cflags])
+
+# Check whether -static-libgcc is supported.
+saved_LDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -static-libgcc"
+AC_MSG_CHECKING([for -static-libgcc])
+AC_LINK_IFELSE([
+  int main() {}], [have_static_libgcc=yes], [have_static_libgcc=no])
+AC_MSG_RESULT($have_static_libgcc); 
+LDFLAGS="$saved_LDFLAGS"
+# Need -Wc to get it through libtool.
+if test "x$have_static_libgcc" = xyes; then
+   ac_lto_plugin_ldflags="-Wc,-static-libgcc"
+fi
+AC_SUBST(ac_lto_plugin_ldflags)
+
+if test x"$host_subdir" = x.; then
+   gcc_build_dir=../gcc
+else
+   gcc_build_dir=../../$host_subdir/gcc
+fi
+AC_SUBST(gcc_build_dir)
+
+# Used for constructing correct paths for offload compilers.
+accel_dir_suffix=
+real_target_noncanonical=${target_noncanonical}
+if test x"$enable_as_accelerator_for" != x; then
+  accel_dir_suffix=/accel/${target_noncanonical}
+  real_target_noncanonical=${enable_as_accelerator_for}
+fi
+AC_SUBST(accel_dir_suffix)
+AC_SUBST(real_target_noncanonical)
+
+# Determine what GCC version number to use in filesystem paths.
+GCC_BASE_VER
+
 AM_PROG_LIBTOOL
 ACX_LT_HOST_FLAGS
 AC_SUBST(target_noncanonical)