diff --git a/build_container b/build_container
new file mode 100755
index 0000000000..181a41140c
--- /dev/null
+++ b/build_container
@@ -0,0 +1,45 @@
+#!/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
+
+TYPE="coreos-buildbot"
+ARCH=$(portageq envvar ARCH)
+DEFAULT_SEED="builds/coreos-sdk/stage4-${ARCH}-latest.tar.bz2"
+DEFAULT_PROFILE="coreos:default/linux/${ARCH}/10.0"
+FORCE_STAGES="stage4"
+
+. "${SCRIPT_ROOT}/lib/catalyst.sh" || exit 1
+
+# include upload options
+. "${BUILD_LIBRARY_DIR}/release_util.sh" || exit 1
+
+## Define the stage4 config template
+catalyst_stage4() {
+cat <<EOF
+target: stage4
+pkgcache_path: $BINPKGS
+stage4/packages: coreos-devel/buildhost-depends
+stage4/fsscript: ${SCRIPT_ROOT}/lib/catalyst_buildbot_stage4.sh
+EOF
+catalyst_stage_default
+}
+
+catalyst_init "$@"
+check_gsutil_opts
+
+if [[ "$STAGES" =~ stage4 ]]; then
+    info "Setting release to ${COREOS_VERSION_STRING}"
+    rm -rf "${TEMPDIR}/stage4_overlay"
+    mkdir -p "${TEMPDIR}/stage4_overlay"
+    "${BUILD_LIBRARY_DIR}/set_lsb_release" \
+        --root "${TEMPDIR}/stage4_overlay" \
+        --production_track sdk --board "${ARCH}-host"
+fi
+
+catalyst_build
+command_completed
diff --git a/lib/catalyst.sh b/lib/catalyst.sh
index e94e4c3b24..e5a2d642d6 100644
--- a/lib/catalyst.sh
+++ b/lib/catalyst.sh
@@ -10,8 +10,14 @@
 : ${TYPE:="coreos-sdk"}
 : ${ARCH:=$(portageq envvar ARCH)}
 : ${DEFAULT_CATALYST_ROOT:="${DEFAULT_BUILD_ROOT}/catalyst"}
-: ${DEFAULT_SEED:="${DEFAULT_CATALYST_ROOT}/builds/${TYPE}/stage4-${ARCH}-latest.tar.bz2"}
+: ${DEFAULT_SEED:="builds/${TYPE}/stage4-${ARCH}-latest.tar.bz2"}
 : ${DEFAULT_PROFILE:="coreos:default/linux/${ARCH}/10.0"}
+# Set to something like "stage4" to restrict what to build
+# FORCE_STAGES=
+
+if [[ "${DEFAULT_SEED}" != /* ]]; then
+    DEFAULT_SEED="${DEFAULT_CATALYST_ROOT}/${DEFAULT_SEED}"
+fi
 
 # Values set in catalyst_init, don't use till after calling it
 CATALYST_ROOT=
@@ -136,7 +142,9 @@ catalyst_init() {
     switch_to_strict_mode
     eval set -- "${FLAGS_ARGV}"
 
-    if [[ $# -eq 0 ]]; then
+    if [[ -n "${FORCE_STAGES}" ]]; then
+        STAGES="${FORCE_STAGES}"
+    elif [[ $# -eq 0 ]]; then
         STAGES="stage1 stage2 stage3 stage4"
     else
         for stage in "$@"; do
diff --git a/lib/catalyst_buildbot_stage4.sh b/lib/catalyst_buildbot_stage4.sh
new file mode 100644
index 0000000000..e2b540a6d2
--- /dev/null
+++ b/lib/catalyst_buildbot_stage4.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+source /tmp/chroot-functions.sh
+
+echo "Double checking everything is fresh and happy."
+run_merge -uDN --with-bdeps=y world