diff --git a/.github/scripts/sync-fetch-kernel.sh b/.github/scripts/sync-fetch-kernel.sh
new file mode 100755
index 0000000..7f2dd7d
--- /dev/null
+++ b/.github/scripts/sync-fetch-kernel.sh
@@ -0,0 +1,75 @@
+#!/bin/bash
+#
+# Set up a Linux repo the way scripts/sync-kernel.sh expects it (see SYNC.md):
+# HEAD at bpf-next's master, and a local bpf-master branch at bpf's master.
+#
+# Both trees are fetched from the kernel-patches/bpf mirror on GitHub, which
+# is more reliable than git.kernel.org. The mirror may lag behind, but its
+# branches have to be in the history of master branches on git.kernel.org.
+
+usage () {
+	echo "USAGE: $0 <libbpf-repo> <linux-repo>"
+	echo ""
+	echo "<linux-repo> is created and must not exist yet."
+	echo "Set MIRROR_URL, BPF_NEXT_URL and BPF_URL to fetch from and check against other repos."
+	exit 1
+}
+
+set -euo pipefail
+
+LIBBPF_REPO=${1-""}
+LINUX_REPO=${2-""}
+
+if [ -z "${LIBBPF_REPO}" ] || [ -z "${LINUX_REPO}" ]; then
+	usage
+fi
+
+# The mirror's bpf-next and bpf branches track master of the respective trees
+MIRROR_URL=${MIRROR_URL:-https://github.com/kernel-patches/bpf.git}
+BPF_NEXT_URL=${BPF_NEXT_URL:-https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git}
+BPF_URL=${BPF_URL:-https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git}
+
+die()
+{
+	echo "Error: $*" >&2
+	exit 1
+}
+
+# Fetching just the commit by its ID wouldn't do: it's already here, and
+# git.kernel.org repos share objects, so it could come from another tree.
+# $1 - mirror's branch
+# $2 - git.kernel.org repo URL
+check_upstream()
+{
+	git fetch -q --no-tags "$2" refs/heads/master || die "can't fetch master from $2"
+	git merge-base --is-ancestor "$1" FETCH_HEAD ||
+		die "mirror's $1 ($(git rev-parse --short "$1")) is not in the history of master in $2"
+}
+
+[ ! -e "${LINUX_REPO}" ] || die "${LINUX_REPO} already exists"
+BPF_NEXT_BASE=$(cat "${LIBBPF_REPO}/CHECKPOINT-COMMIT")
+BPF_BASE=$(cat "${LIBBPF_REPO}/BPF-CHECKPOINT-COMMIT")
+
+git init -q -b master "${LINUX_REPO}"
+cd "${LINUX_REPO}"
+git config gc.auto 0
+
+echo "Fetching bpf-next and bpf from ${MIRROR_URL}..."
+git fetch -q --no-tags "${MIRROR_URL}" \
+	+refs/heads/bpf-next:refs/remotes/bpf-next/master \
+	+refs/heads/bpf:refs/remotes/bpf/master
+
+echo "Checking them against git.kernel.org..."
+check_upstream bpf-next/master "${BPF_NEXT_URL}"
+check_upstream bpf/master "${BPF_URL}"
+
+git merge-base --is-ancestor "${BPF_NEXT_BASE}" bpf-next/master ||
+	die "checkpoint ${BPF_NEXT_BASE} is not in bpf-next's history; if it was rebased away upstream, update the checkpoint manually"
+git merge-base --is-ancestor "${BPF_BASE}" bpf/master ||
+	die "checkpoint ${BPF_BASE} is not in bpf's history; if it was rebased away upstream, update the checkpoint manually"
+
+git checkout -q -B master bpf-next/master
+git branch -q -f bpf-master bpf/master
+
+echo "bpf-next tip: $(git log -n1 --pretty='%h ("%s")' master)"
+echo "bpf tip:      $(git log -n1 --pretty='%h ("%s")' bpf-master)"