diff --git a/build.sh b/build.sh
index 42df957..d10109f 100755
--- a/build.sh
+++ b/build.sh
@@ -1,19 +1,87 @@
-#!/bin/sh
+#!/bin/bash
 
-export COREOS_ASSEMBLER_CONTAINER=quay.io/coreos-assembler/coreos-assembler:v0.9.0
+output="$HOME/tmp/itix-coreos"
+target="$output/cosa-output"
+repo="$output/ostree-repo"
+build_repo="$output/ostree-build-repo"
+git="$PWD"
+# Set the corresponding backend using "rclone config"
+s3_bucket="backblaze:itix-ostree"
+
+function message() {
+  echo
+  echo ">>>" "$@"
+  echo
+}
 
 function cosa() {
-  echo -e "\n>>> cosa" "$@" "\n"
-  podman run --rm -ti --security-opt label=disable --privileged --user root                        \
-             -v $PWD/cosa/:/srv/ --device /dev/kvm --device /dev/fuse                              \
-             --tmpfs /tmp -v /var/tmp:/var/tmp --name cosa -v ${PWD}:/git:ro                       \
-             ${COREOS_ASSEMBLER_CONTAINER_RUNTIME_ARGS} ${COREOS_ASSEMBLER_CONTAINER} "$@"
+  message "Running cosa $1..."
+  set -x
+  podman run --rm -ti --security-opt label=disable --privileged --user=root                        \
+             -v ${PWD}:/srv/ --device /dev/kvm --device /dev/fuse                                  \
+             --tmpfs /tmp -v /var/tmp:/var/tmp --name cosa                                         \
+             ${COREOS_ASSEMBLER_CONFIG_GIT:+-v $COREOS_ASSEMBLER_CONFIG_GIT:/srv/src/config/:ro}   \
+             ${COREOS_ASSEMBLER_GIT:+-v $COREOS_ASSEMBLER_GIT/src/:/usr/lib/coreos-assembler/:ro}  \
+             ${COREOS_ASSEMBLER_CONTAINER_RUNTIME_ARGS}                                            \
+             ${COREOS_ASSEMBLER_CONTAINER:-quay.io/coreos-assembler/coreos-assembler:latest} "$@"
+  rc=$?
+  set +x
+  if [ $rc -gt 0 ]; then
+    echo 'coreos-assembler failed. Stopping here!'
+    exit 1
+  fi
+  return $rc
 }
 
-set -e
-if [ ! -e cosa ]; then
-  mkdir -p cosa
-  cosa init /git
+message "Performing a sanity check on overlay.d..."
+
+need_attention=0
+for f in fedora-coreos-config/overlay.d/[0-9][0-9]*; do
+  basename="$(basename $f)"
+  if [ ! -e "overlay.d/$basename" ]; then
+    echo
+    echo "WARNING: $f is missing from the top-level overlay.d!"
+    echo
+    need_attention=1
+  fi
+done
+
+if [ "$need_attention" == "1" ]; then
+  echo "Heads up! Some overlay files from upstream are missing in your top-level git repository. Your build may be incomplete..."
+  read -t 5 -p "Press any key to continue."
+fi
+
+
+if [ ! -e "$target" ]; then
+  mkdir -p "$target" || exit 1
+  cd "$target" || exit 1
+  # cosa init skaffolds the folder hierarchy needed for cosa fetch
+  # and cosa build. We supply a dummy Git repository here since it is needed.
+  # However, we will override it later with the current directory.
+  cosa init https://github.com/coreos/fedora-coreos-config.git
+else
+  cd "$target" || exit 1
 fi
+
+export COREOS_ASSEMBLER_CONFIG_GIT="$git"
 cosa fetch
-cosa build ostree
+cosa build
+
+message "Extracting generated ostree..."
+rm -rf "$build_repo" || exit 1
+mkdir -p "$build_repo"
+tar -xf "$target"/builds/latest/x86_64/fedora-coreos-*-ostree.x86_64.tar -C "$build_repo"
+
+if [ ! -e "$repo/config" ]; then
+  message "Initializing a new ostree repository..."
+  mkdir -p "$repo" || exit 1
+  ostree init --repo="$repo" --mode=archive || exit 1
+fi
+
+message "Importing the new commit..."
+ostree --repo="$repo" pull-local "$build_repo" itix/x86_64/coreos/stable || exit 1
+message "Generating static delta files (though it may fail if there is no parent commit)..."
+ostree --repo="$repo" static-delta generate itix/x86_64/coreos/stable
+
+message "Mirroring the repository to Backblaze B2..."
+rclone sync -P "$repo" "$s3_bucket"
diff --git a/manifest-lock.overrides.aarch64.yaml b/manifest-lock.overrides.aarch64.yaml
new file mode 120000
index 0000000..4909b2e
--- /dev/null
+++ b/manifest-lock.overrides.aarch64.yaml
@@ -0,0 +1 @@
+fedora-coreos-config/manifest-lock.overrides.aarch64.yaml
\ No newline at end of file
diff --git a/manifest-lock.overrides.ppc64le.yaml b/manifest-lock.overrides.ppc64le.yaml
new file mode 120000
index 0000000..f31dca3
--- /dev/null
+++ b/manifest-lock.overrides.ppc64le.yaml
@@ -0,0 +1 @@
+fedora-coreos-config/manifest-lock.overrides.ppc64le.yaml
\ No newline at end of file
diff --git a/manifest-lock.overrides.s390x.yaml b/manifest-lock.overrides.s390x.yaml
new file mode 120000
index 0000000..570eb42
--- /dev/null
+++ b/manifest-lock.overrides.s390x.yaml
@@ -0,0 +1 @@
+fedora-coreos-config/manifest-lock.overrides.s390x.yaml
\ No newline at end of file
diff --git a/manifest-lock.overrides.x86_64.yaml b/manifest-lock.overrides.x86_64.yaml
new file mode 120000
index 0000000..f5b6296
--- /dev/null
+++ b/manifest-lock.overrides.x86_64.yaml
@@ -0,0 +1 @@
+fedora-coreos-config/manifest-lock.overrides.x86_64.yaml
\ No newline at end of file
diff --git a/manifest-lock.x86_64.json b/manifest-lock.x86_64.json
new file mode 120000
index 0000000..90df43a
--- /dev/null
+++ b/manifest-lock.x86_64.json
@@ -0,0 +1 @@
+fedora-coreos-config/manifest-lock.x86_64.json
\ No newline at end of file