diff --git a/chroot_version_hooks.d/8_unmerge_gmp b/chroot_version_hooks.d/8_unmerge_gmp
new file mode 100644
index 0000000000..f5dbb4300d
--- /dev/null
+++ b/chroot_version_hooks.d/8_unmerge_gmp
@@ -0,0 +1,18 @@
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Unmerge dev-libs/gmp in all boards where it's still linked against the old
+# version.
+for board_root in /build/*; do
+  board=$(basename "${board_root}")
+  emerge_board=$(which emerge-${board} 2>/dev/null || true)
+  scanelf_out=$(scanelf -qn ${board_root}/usr/lib/libgmpxx.so.4 || true)
+  if [ -x "${emerge_board}" ] && [[ "$scanelf_out" == *libgmp.so.3* ]]; then
+    CLEAN_DELAY=0 ${emerge_board} --unmerge dev-libs/gmp || true
+    eclean-${board} -d packages || true
+  fi
+done
+
+info "Chroot upgraded to version 8: Unmerge old dev-libs/gmp"
+exit 0