diff --git a/branch_release b/branch_release
index 631acfa4cf..f321eef027 100755
--- a/branch_release
+++ b/branch_release
@@ -7,9 +7,6 @@
 SCRIPT_ROOT=$(dirname $(readlink -f "$0"))
 . "${SCRIPT_ROOT}/common.sh" || exit 1
 
-COREOS_EPOCH=1372636800  # Mon Jul  1 00:00:00 UTC 2013
-TODAYS_VERSION=$(( (`date +%s` - ${COREOS_EPOCH}) / 86400 ))
-
 DEFINE_integer build "${TODAYS_VERSION}" \
     "Branch name (aka 'build'), should be days since 2013-7-1"
 DEFINE_integer branch 0 "Branch revision, should be 0"
diff --git a/common.sh b/common.sh
index 69299f06c1..588a0254d0 100644
--- a/common.sh
+++ b/common.sh
@@ -315,6 +315,12 @@ fi
 # Full version string.
 COREOS_VERSION_STRING="${COREOS_BUILD}.${COREOS_BRANCH}.${COREOS_PATCH}"
 
+# Calculate what today's build version should be, used by release
+# scripts to provide a reasonable default value. The value is the number
+# of days since COREOS_EPOCH, Mon Jul  1 00:00:00 UTC 2013
+readonly COREOS_EPOCH=1372636800
+TODAYS_VERSION=$(printf "%04d" $(( (`date +%s` - ${COREOS_EPOCH}) / 86400 )) )
+
 # Load developer's custom settings.  Default location is in scripts dir,
 # since that's available both inside and outside the chroot.  By convention,
 # settings from this file are variables starting with 'CHROMEOS_'
diff --git a/master_release b/master_release
new file mode 100755
index 0000000000..038e53bcbf
--- /dev/null
+++ b/master_release
@@ -0,0 +1,33 @@
+#!/bin/bash
+
+# Copyright (c) 2013 The CoreOS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+SCRIPT_ROOT=$(dirname $(readlink -f "$0"))
+. "${SCRIPT_ROOT}/common.sh" || exit 1
+
+DEFINE_string master "master" "Manifest master branch to update."
+DEFINE_string branch "build-${TODAYS_VERSION}" \
+    "Manifest branch, tag, or other ref to get version from."
+DEFINE_boolean push ${FLAGS_FALSE} "Push to public manifest repository."
+DEFINE_string remote "origin" "Remote name or URL to push to."
+
+# Parse flags
+FLAGS "$@" || exit 1
+eval set -- "${FLAGS_ARGV}"
+switch_to_strict_mode
+
+info "Running repo init -b ${FLAGS_master}"
+repo init -b "${FLAGS_master}"
+
+info "Updating version.txt from ${FLAGS_branch}"
+cd "${GCLIENT_ROOT}/.repo/manifests"
+git checkout "${FLAGS_branch}" version.txt
+git add version.txt
+git commit -m "bump(version): Update version from ${FLAGS_branch}"
+
+if [[ ${FLAGS_push} -eq ${FLAGS_TRUE} ]]; then
+    info "Pushing to ${FLAGS_remote} ${FLAGS_master}"
+    git push "${FLAGS_remote}" "HEAD:refs/heads/${FLAGS_master}"
+fi