diff --git a/src/build_rpm_from_dir b/src/build_rpm_from_dir
deleted file mode 100755
index 1d2499e008..0000000000
--- a/src/build_rpm_from_dir
+++ /dev/null
@@ -1,55 +0,0 @@
-#!/bin/bash
-set -euo pipefail
-
-srcdir=$1; shift
-name=$1; shift
-outdir=$1; shift
-
-sha256=$(cd "${srcdir}" && find . ! -type d -print0 | xargs -0 -r sha256sum \
-            | sha256sum | cut -f 1 -d ' ')
-
-latest_rpm=$(find "$outdir/" -iname "$name-*.rpm" | sort -Vr | head -n 1)
-
-if rpm -qp "$latest_rpm" --qf '%{DESCRIPTION}' | grep -q "(sha256:$sha256)"; then
-    echo "Re-using ${latest_rpm} ($sha256)."
-    exit 0
-fi
-
-# shellcheck disable=SC2154
-cat > "$name.spec" << EOF
-Name: $name
-Version: $(date +%s)
-Release: ${sha256::7}
-BuildArch: noarch
-Summary: $summary overlay
-License: $license
-# this shows up then in rpm -qi (XXX: don't hardcode this)
-URL: https://github.com/coreos/fedora-coreos-config
-
-BuildRequires: rsync
-
-%description
-%{summary} (sha256:$sha256)
-
-%build
-# Nothing to build
-
-%install
-rsync -av "${srcdir}/" %{buildroot}
-
-%files
-$(cd "${srcdir}" && find . ! -type d | cut -c 2-)
-EOF
-
-rm -rf rpms
-rpmbuild -ba \
-  --define "_sourcedir $PWD" \
-  --define "_specdir $PWD" \
-  --define "_builddir $PWD/.build" \
-  --define "_srcrpmdir $PWD/rpms" \
-  --define "_rpmdir $PWD/rpms" \
-  --define "_buildrootdir $PWD/.buildroot" "$name.spec"
-
-# delete any older RPMs first
-rm -f "$outdir/$name"-*.rpm
-cp rpms/noarch/*.rpm "$outdir"
diff --git a/src/cmdlib.sh b/src/cmdlib.sh
index b9a843b28c..397cb2e61b 100755
--- a/src/cmdlib.sh
+++ b/src/cmdlib.sh
@@ -239,6 +239,11 @@ runcompose() {
     local overridesdir=${workdir}/overrides
     local tmp_overridesdir=${TMPDIR}/override
     local override_manifest="${tmp_overridesdir}"/coreos-assembler-override-manifest.yaml
+
+    local git_timestamp="January 1 1970"
+    if [ -d "${configdir_gitrepo}/.git" ]; then
+        git_timestamp=$(git -C "${configdir_gitrepo}" show -s --format=%ci HEAD)
+    fi
     if [ -d "${overridesdir}" ] || [ -n "${ref_is_temp}" ] || [ -d "${configdir}/overlay" ]; then
         mkdir "${tmp_overridesdir}"
         cat > "${override_manifest}" <<EOF
@@ -254,13 +259,14 @@ EOF
         echo 'ref: "'"${ref}"'"' >> "${override_manifest}"
     fi
     if [ -d "${configdir}/overlay" ]; then
+        echo -n "Committing ${configdir}/overlay... "
+        ostree commit --repo="${tmprepo}" --tree=dir="${configdir}/overlay" -b "${name}-config-overlay" \
+          --owner-uid 0 --owner-gid 0 --no-xattrs --no-bindings --parent=none \
+          --timestamp "${git_timestamp}"
         cat >> "${override_manifest}" <<EOF
-packages:
-  - ${name}-overlay
+ostree-layers:
+  - ${name}-config-overlay
 EOF
-        mkdir -p "${overridesdir}"/rpm
-        mkdir tmp/overlay-build
-        (cd tmp/overlay-build && "${DIR}"/build_rpm_from_dir "${configdir}/overlay" "${name}-overlay" "${workdir}/overrides/rpm")
     fi
     if [[ -n $(ls "${overridesdir}/rpm/"*.rpm 2> /dev/null) ]]; then
         (cd "${overridesdir}"/rpm && createrepo_c .)
@@ -278,9 +284,10 @@ EOF
     fi
     rootfs_overlay="${overridesdir}/rootfs"
     if [ -d "${rootfs_overlay}" ]; then
-        echo "Committing ${rootfs_overlay}"
-        sudo ostree commit --repo="${workdir}/tmp/repo" --tree=dir="${rootfs_overlay}" -b cosa-bin-overlay \
-          --owner-uid 0 --owner-gid 0 --no-xattrs --no-bindings --parent=none
+        echo -n "Committing ${rootfs_overlay}... "
+        ostree commit --repo="${tmprepo}" --tree=dir="${rootfs_overlay}" -b cosa-bin-overlay \
+          --owner-uid 0 --owner-gid 0 --no-xattrs --no-bindings --parent=none \
+          --timestamp "${git_timestamp}"
           cat >> "${override_manifest}" << EOF
 ostree-override-layers:
   - cosa-bin-overlay