diff --git a/config/ChangeLog b/config/ChangeLog
index aa63efdc0ec..bebc20ee075 100644
--- a/config/ChangeLog
+++ b/config/ChangeLog
@@ -1,3 +1,9 @@
+2018-05-08  Richard Biener  <rguenther@suse.de>
+
+	PR bootstrap/85571
+	* bootstrap-lto-noplugin.mk: Disable compare.
+	* bootstrap-lto.mk: Supply contrib/compare-lto for do-compare.
+
 2018-04-24  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR bootstrap/85490
diff --git a/config/bootstrap-lto-noplugin.mk b/config/bootstrap-lto-noplugin.mk
index 0ca8ee2ff01..0f50708e49d 100644
--- a/config/bootstrap-lto-noplugin.mk
+++ b/config/bootstrap-lto-noplugin.mk
@@ -6,3 +6,4 @@ STAGE3_CFLAGS += -flto=jobserver -frandom-seed=1 -ffat-lto-objects
 STAGEprofile_CFLAGS += -flto=jobserver -frandom-seed=1
 STAGEtrain_CFLAGS += -flto=jobserver -frandom-seed=1
 STAGEfeedback_CFLAGS += -flto=jobserver -frandom-seed=1
+do-compare = /bin/true
diff --git a/config/bootstrap-lto.mk b/config/bootstrap-lto.mk
index 50b86ef1c81..768b6337bd6 100644
--- a/config/bootstrap-lto.mk
+++ b/config/bootstrap-lto.mk
@@ -13,3 +13,5 @@ LTO_RANLIB = $$r/$(HOST_SUBDIR)/prev-gcc/gcc-ranlib$(exeext) -B$$r/$(HOST_SUBDIR
 LTO_EXPORTS = AR="$(LTO_AR)"; export AR; \
 	      RANLIB="$(LTO_RANLIB)"; export RANLIB;
 LTO_FLAGS_TO_PASS = AR="$(LTO_AR)" RANLIB="$(LTO_RANLIB)"
+
+do-compare = $(SHELL) $(srcdir)/contrib/compare-lto $$f1 $$f2
diff --git a/contrib/ChangeLog b/contrib/ChangeLog
index e284d8933ce..6c184f766b7 100644
--- a/contrib/ChangeLog
+++ b/contrib/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-08  Richard Biener  <rguenther@suse.de>
+
+	PR bootstrap/85571
+	* compare-lto: New script derived from compare-debug.
+
 2018-05-02  Jakub Jelinek  <jakub@redhat.com>
 
 	* gennews (files): Add files for GCC 8.
diff --git a/contrib/compare-lto b/contrib/compare-lto
new file mode 100755
index 00000000000..17379e196a7
--- /dev/null
+++ b/contrib/compare-lto
@@ -0,0 +1,111 @@
+#! /bin/sh
+
+# Compare copies of two given object files.
+
+# Copyright (C) 2007, 2008, 2009, 2010, 2012 Free Software Foundation
+# Originally by Alexandre Oliva <aoliva@redhat.com>
+# Modified for LTO bootstrap by Richard Biener <rguenther@suse.de>
+
+# This file is part of GCC.
+
+# GCC is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 3, or (at your option) any later
+# version.
+
+# GCC is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+rm='rm -f'
+
+case $1 in
+-p | --preserve)
+  rm='echo preserving'
+  shift
+  ;;
+esac
+
+if test $# != 2; then
+  echo 'usage: compare-lto file1.o file2.o' >&2
+  exit 1
+fi
+
+if test ! -f "$1"; then
+  echo "$1" does not exist >&2
+  exit 1
+fi
+
+if test ! -f "$2"; then
+  echo "$2" does not exist >&2
+  exit 1
+fi
+
+suf1=stripped
+while test -f "$1.$suf1"; do
+  suf1=$suf1.
+done
+
+suf2=stripped
+while test -f "$2.$suf2"; do
+  suf2=$suf2.
+done
+
+trap 'rm -f "$1.$suf1" "$2.$suf2"' 0 1 2 15
+
+if cmp "$1" "$2"; then
+  status=0
+else
+  status=1
+
+  cmd=
+  for t in objdump readelf eu-readelf; do
+    if ($t --help) 2>&1 | grep ' --\[*section-\]*headers' > /dev/null; then
+      cmd=$t
+      break
+    fi
+  done
+
+  # If there are LTO option sections, try to strip them off.
+  if test "x$cmd" = "x" ||
+     $cmd --section-headers "$1" | grep '.gnu.lto_.opts' > /dev/null ||
+     $cmd --section-headers "$2" | grep '.gnu.lto_.opts' > /dev/null ; then
+
+    echo stripping off LTO option section, then retrying >&2
+
+    seclist=".gnu.lto_.opts"
+    rsopts=`for sec in $seclist; do echo " --remove-section $sec"; done`
+
+    if (objcopy -v) 2>&1 | grep ' --remove-section' > /dev/null; then
+      objcopy $rsopts "$1" "$1.$suf1"
+      objcopy $rsopts "$2" "$2.$suf2"
+    elif (strip --help) 2>&1 | grep ' --remove-section' > /dev/null; then
+      cp "$1" "$1.$suf1"
+      strip $rsopts "$1.$suf1"
+
+      cp "$2" "$2.$suf2"
+      strip $rsopts "$2.$suf2"
+    else
+      echo failed to strip off LTO option section >&2
+    fi
+
+    trap 'rm -f "$1.$suf1" "$2.$suf2"' 0 1 2 15
+
+    if cmp "$1.$suf1" "$2.$suf2"; then
+      status=0
+    else
+      status=1
+    fi
+  fi
+fi
+
+$rm "$1.$suf1" "$2.$suf2"
+
+trap "exit $status; exit" 0 1 2 15
+
+exit $status