diff --git a/chroot_version_hooks.d/157_unmerge_libunwind b/chroot_version_hooks.d/157_unmerge_libunwind
new file mode 100644
index 0000000..c77fa6f
--- /dev/null
+++ b/chroot_version_hooks.d/157_unmerge_libunwind
@@ -0,0 +1,8 @@
+# Copyright 2018 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.
+
+# sys-libs/libunwind got replaced by sys-libs/llvm-libunwind, so clean out the
+# old one. Eat errors if the package has already been unmerged.
+
+sudo qmerge -Uqy sys-libs/libunwind || true