diff --git a/.github/workflows/subtree_push.yml b/.github/workflows/subtree_push.yml
new file mode 100644
index 00000000000..1e34d9ae09f
--- /dev/null
+++ b/.github/workflows/subtree_push.yml
@@ -0,0 +1,22 @@
+name: Git Subtree Push
+on:
+  workflow_dispatch:
+  # no inputs at this time
+
+jobs:
+  subtree-push:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: checkout
+      uses: actions/checkout@v4
+
+    # Based on https://github.com/rust-lang/rustup/issues/3409
+    # rustup should already be installed in GitHub Actions.
+    - name: install current toolchain with rustup
+      run: |
+        CURRENT_TOOLCHAIN=$(cut -d ' ' -f3 <<< $(cat rust-toolchain | grep "channel =") | tr -d '"')
+        rustup install $CURRENT_TOOLCHAIN
+
+    - name: subtree-push
+      run: ${GITHUB_WORKSPACE}/ci/subtree_sync.sh subtree-push
diff --git a/ci/subtree_sync.sh b/ci/subtree_sync.sh
new file mode 100755
index 00000000000..b66074d8190
--- /dev/null
+++ b/ci/subtree_sync.sh
@@ -0,0 +1,285 @@
+#!/bin/bash
+
+# Install the latest nightly rust toolchain
+# We want to perform a subtree-push from the latest nightly rust-lang/rust -> rustfmt
+# In order to do so, make sure we've go the latest nightly toolchain installed
+function install_latest_nightly() {
+    rustup update nightly --no-self-update
+}
+
+# Follows the steps outlined in the Clippy docs to get a patched version of git-subtree that works
+# with larger repos.
+# This is necessary to push commits from rust-lang/rust -> rustfmt
+# https://doc.rust-lang.org/nightly/clippy/development/infrastructure/sync.html#patching-git-subtree-to-work-with-big-repos
+function get_patched_subtree() {
+    local CLONE_DIR=$1
+    local PATCHED_GIT_SUBTREE_FORK="https://github.com/tqc/git.git"
+    local PATCHED_BRANCH="tqc/subtree"
+
+    GIT_TERMINAL_PROMPT=0 git clone --branch $PATCHED_BRANCH --single-branch --quiet --depth 1 $PATCHED_GIT_SUBTREE_FORK $CLONE_DIR
+
+    local SUBTREE_SCRIPT_PATH="contrib/subtree/git-subtree.sh"
+    local FULL_SUBTREE_SCRIPT_PATH="$CLONE_DIR/$SUBTREE_SCRIPT_PATH"
+    chmod +x $FULL_SUBTREE_SCRIPT_PATH
+    echo "$FULL_SUBTREE_SCRIPT_PATH"
+}
+
+# Extract various peices of info from the rustc verbose version output e.g `rustc -Vv`
+function parse_rustc_verbose_version_info() {
+    local RUSTC_VERBOSE_VERSION_INFO=$1
+    # valid values are: `binary`, `commit-hash`, `commit-date`, `host`, `release`, `LLVM version`
+    local INFO_KEY=$2
+    echo $(cut -d ' ' -f2  <<< $(echo "$RUSTC_VERBOSE_VERSION_INFO=" | grep "$INFO_KEY:"))
+}
+
+# Parses the `commit-hash` from rustc verbose version output e.g `rustc -Vv`
+function get_commit_hash() {
+    local RUSTC_VERBOSE_VERSION_INFO=$1
+    echo $(parse_rustc_verbose_version_info "$RUSTC_VERBOSE_VERSION_INFO" "commit-hash")
+}
+
+# Parses the `commit-date` from rustc verbose version output e.g `rustc -Vv`
+function get_commit_date() {
+    local RUSTC_VERBOSE_VERSION_INFO==$1
+    echo $(parse_rustc_verbose_version_info "$RUSTC_VERBOSE_VERSION_INFO" "commit-date")
+}
+
+# Parses the `release` from rustc verbose version output e.g `rustc -Vv`
+function get_release_number() {
+    local RUSTC_VERBOSE_VERSION_INFO==$1
+    echo $(parse_rustc_verbose_version_info "$RUSTC_VERBOSE_VERSION_INFO" "release")
+}
+
+# The nightly toolchain always has a commit date that is 1 day behind.
+# This will help us get the correct release date for the toolchain
+function toolchain_date() {
+    # Should be a date string in the form YYYY-MM-DD.
+    # We should get this date using `get_commit_date`
+    local DATE=$1
+    echo $(date --rfc-3339=date --date="$DATE+1day")
+}
+
+# Sets the new toolchain version in rustfmt's `rust-toolchain` file
+function bump_rust_toolchain_version() {
+    local CURRENT_TOOLCHAIN=$1
+    local LATEST_TOOLCHAIN=$2
+    local TOOLCHAIN_FILE="rust-toolchain"
+    NEW_TOOLCHAIN_FILE=$(cat $TOOLCHAIN_FILE | sed "s/$CURRENT_TOOLCHAIN/$LATEST_TOOLCHAIN/g")
+    echo "$NEW_TOOLCHAIN_FILE" > $TOOLCHAIN_FILE
+}
+
+# Clone the master branch of the rust-lang/rust repo
+function clone_rustlang_rust() {
+    local CLONE_DIR=$1
+    local LAST_SUBTREE_PUSH_COMMIT=$2
+    RUST_LANG_RUST_GIT_URL="https://github.com/rust-lang/rust.git"
+    # Do we need the entire git history? Would it suffice to just get the history from the last full subtree sync?
+    git clone --branch master --single-branch $RUST_LANG_RUST_GIT_URL $CLONE_DIR
+    cd $CLONE_DIR
+}
+
+# Follows instructions outlined by the Clippy docs to perform a subtree push
+# https://doc.rust-lang.org/nightly/clippy/development/infrastructure/sync.html#syncing-changes-between-clippy-and-rust-langrust
+function rustc_to_rustfmt_subtree_push() {
+    local CLONE_DIR=$1
+    local LATEST_NIGHTLY_COMMIT=$2
+    local LAST_SUBTREE_PUSH_COMMIT=$3
+    local RUSTFMT_LOCAL_PATH=$4
+    local NEW_BRANCH_NAME=$5
+    local LOCAL_RUSTFMT_REPO_ALIAS="rustfmt-local"
+    # Path to the rustfmt subtree within the rust-lang/rust repo
+    local RUSTFMT_TOOLS_PATH="src/tools/rustfmt"
+
+    SUBTREE_COMMAND=$(get_patched_subtree "$CLONE_DIR/git")
+
+    # cloning will also CD into the rust-lang/rust repo
+    clone_rustlang_rust "$CLONE_DIR/rust" $LAST_SUBTREE_PUSH_COMMIT
+    git remote add $LOCAL_RUSTFMT_REPO_ALIAS $RUSTFMT_LOCAL_PATH
+
+    # The subtree-push doesn't necessarily happen with the HEAD of the rust-lang/rust repo.
+    # We want to `push` changes up to whatever commit was last released.
+    git switch --detach $LATEST_NIGHTLY_COMMIT
+    $SUBTREE_COMMAND push -P $RUSTFMT_TOOLS_PATH $LOCAL_RUSTFMT_REPO_ALIAS $NEW_BRANCH_NAME
+}
+
+# Tries to create a merge commit for the latest subtree-push
+# A merge commit is only created if the changes from rust-lang/rust apply cleanly to rustfmt.
+function try_create_subtree_push_merge_commit() {
+    local RUSTFMT_REPO_PATH=$1
+    local NEW_BRANCH_NAME=$2
+    local COMMIT_AUTHOR=$3
+
+    cd $RUSTFMT_REPO_PATH
+    git fetch origin master
+    git switch $NEW_BRANCH_NAME
+
+    git merge origin/master --no-ff --no-commit
+    if [ $? -eq 0 ]; then
+        # The subtree push was clean :)
+        git commit --author "$COMMIT_AUTHOR"
+        return 0
+    else
+        # Unfortunately there are merge conflicts that need to be addressed :(
+        git merge --abort
+        return 1
+    fi
+}
+
+function create_subtree_push_pull_request() {
+    local CLEAN_MERGE_COMMIT=$1
+    local CURRENT_TOOLCHAIN=$2
+    local LATEST_TOOLCHAIN=$3
+    local COMMIT_AUTHOR=$4
+    local COMMIT_MESSAGE=$5
+    local NEW_BRANCH_NAME=$6
+
+    # This is one of the default environment variables set by GitHub Actions
+    # https://docs.github.com/en/actions/learn-github-actions/variables#default-environment-variables
+    local GITHUB_REPOSITORY=$GITHUB_REPOSITORY
+
+    if [ $CLEAN_MERGE_COMMIT -eq 0 ]; then
+        # No merge conflicts!!
+        bump_rust_toolchain_version "$CURRENT_TOOLCHAIN" "$LATEST_TOOLCHAIN"
+        git add rust-toolchain
+        git commit --author "$COMMIT_AUTHOR" -m "$COMMIT_MESSAGE"
+    fi
+
+    # whether the merge commit applied cleanly or not create a PR
+    # I believe the remote repo will always be `origin` in GitHub Actions
+    git push origin $NEW_BRANCH_NAME
+    # Skip the title of the commit
+    local PR_MESSAGE=$(echo "$COMMIT_MESSAGE" | tail -n +2)
+    local PR_URL=$(gh pr create --title "subtree-push $LATEST_TOOLCHAIN" --body "$PR_MESSAGEE")
+
+    if [ $CLEAN_MERGE_COMMIT -eq 0 ]; then
+        gh pr comment $PR_URL --body "The subtree-push applied cleanly ✅.
+
+Take a moment to review the changes. You'll also want to Run the [Diff-Check] job.
+
+**Diff-Check Job Parameters**:
+- Git URL: https://github.com/$GITHUB_REPOSITORY.git
+- Feature Branch: $NEW_BRANCH_NAME
+
+After CI and the [Diff-Check] job pass this PR should be good to merge!
+
+[Diff-Check]: https://github.com/rust-lang/rustfmt/actions/workflows/check_diff.yml
+"
+    else
+        gh pr comment $PR_URL --body "The subtree-push can't be automatically merged ⚠️
+
+1. Please checkout branch \`$NEW_BRANCH_NAME\`, fix any merge conflicts, and then run \`git merge upstream/master --no-ff\`
+2. Bump the toolchain listed in the \`rust-toolchain\` file to $LATEST_TOOLCHAIN, and commit those changes.
+   Here's a commit message you might use:
+   \`\`\`
+   $COMMIT_MESSAGE
+   \`\`\`
+3. Wait for CI checks to pass.
+"
+    fi
+
+    # TODO(ytmimi): notify the team that a new subtree-push PR was created.
+    # Additionally, include whether the subtree-push applied cleanly or not.
+    # miri publishes messages to Zulip. I feel like we could do the same.
+    # https://github.com/rust-lang/miri/blob/f006d42618a038f7e38d2b59d1b0664727e51382/.github/workflows/ci.yml#L205-L210
+}
+
+# Create a new Pull Request in the rustfmt repository for the git subtree-push
+#
+# **Note:** The Pull Request is created regardless if the changes from rust-lang/rust
+# apply cleanly to rustfmt or not. If they apply cleanly, then great! All that's left to
+# do is review and merge the changes. If there are conflicts one of the rustfmt maintainers
+# will need to address those, create a merge commit
+function run_rustfmt_subtree_push() {
+    local COMMIT_AUTHOR=$1
+
+    # Assumes that the current working directory is the root of the rustfmt repo
+    local CWD=$(pwd)
+    # TMP DIR used to clone the rust-lang/rust repo and a patched `git subtree` command
+    local TMP_DIR=$(mktemp -d -t $REPO_NAME-XXXXXXXX)
+
+    # Running `rustc -Vv` in the rustfmt repo should give us details for the nightly toolchain
+    # specified in the `rust-toolchain` file
+    CURRENT_RUSTFMT_RUSTC_VERSION=$(rustc -Vv)
+    CURRENT_RUSTFMT_RUSTC_COMMIT_HASH=$(get_commit_hash "$CURRENT_RUSTFMT_RUSTC_VERSION")
+    CURRENT_RUSTFMT_RUSTC_COMMIT_DATE=$(get_commit_date "$CURRENT_RUSTFMT_RUSTC_VERSION")
+    CURRENT_RUSTFMT_RUSTC_RELEASE=$(get_release_number "$CURRENT_RUSTFMT_RUSTC_VERSION")
+    CURRENT_TOOLCHAIN_DATE=$(toolchain_date "$CURRENT_RUSTFMT_RUSTC_COMMIT_DATE")
+    CURRENT_TOOLCHAIN="nightly-$CURRENT_TOOLCHAIN_DATE"
+
+    echo $CURRENT_TOOLCHAIN
+
+    # Running `rustc +nightly -Vv` should give us details about the latest nightly toolchain
+    LATEST_NIGHTLY_RUSTC_VERSION=$(rustc +nightly -Vv)
+    LATEST_NIGHTLY_RUSTC_COMMIT_HASH=$(get_commit_hash "$LATEST_NIGHTLY_RUSTC_VERSION")
+    LATEST_NIGHTLY_COMMIT_DATE=$(get_commit_date "$LATEST_NIGHTLY_RUSTC_VERSION")
+    LATEST_NIGHTLY_RELEASE=$(get_release_number "$LATEST_NIGHTLY_RUSTC_VERSION")
+    LATEST_TOOLCHAIN_DATE=$(toolchain_date "$LATEST_NIGHTLY_COMMIT_DATE")
+    LATEST_TOOLCHAIN="nighlty-$LATEST_TOOLCHAIN_DATE"
+
+    echo $LATEST_TOOLCHAIN
+
+    COMMIT_MESSAGE="chore: bump rustfmt toolchain from $CURRENT_TOOLCHAIN -> $LATEST_TOOLCHAIN
+
+Bumping the toolchain version as part of a git subtree push
+
+current toolchain ($CURRENT_TOOLCHAIN):
+  - $CURRENT_RUSTFMT_RUSTC_RELEASE (${CURRENT_RUSTFMT_RUSTC_COMMIT_HASH:0:9} $CURRENT_RUSTFMT_RUSTC_COMMIT_DATE)
+
+latest toolchain ($LATEST_TOOLCHAIN):
+  - $LATEST_NIGHTLY_RELEASE (${LATEST_NIGHTLY_RUSTC_COMMIT_HASH:0:9} $LATEST_NIGHTLY_COMMIT_DATE)
+"
+
+    NEW_BRANCH_NAME="subtree-push-$LATEST_TOOLCHAIN"
+
+    rustc_to_rustfmt_subtree_push \
+        $TMP_DIR \
+        $LATEST_NIGHTLY_RUSTC_COMMIT_HASH \
+        $CURRENT_RUSTFMT_RUSTC_COMMIT_HASH \
+        $CWD \
+        $NEW_BRANCH_NAME
+
+
+    # Jump back to rustfmt after creating the subtree push in the rust-lang/rust repo
+    cd $CWD
+    git swich $NEW_RUSTFMT_BRANCH
+
+    try_create_subtree_push_merge_commit $CWD $NEW_BRANCH_NAME $COMMIT_AUTHOR
+    CLEAN_MERGE_COMMIT=$?
+
+    create_subtree_push_pull_request \
+        $CLEAN_MERGE_COMMIT \
+        $CURRENT_TOOLCHAIN \
+        $LATEST_TOOLCHAIN \
+        "$COMMIT_AUTHOR" \
+        "$COMMIT_MESSAGE" \
+        $NEW_BRANCH_NAME
+
+    rm -rf $TMP_DIR
+}
+
+function print_help() {
+    echo "Tools to help automate subtree syncs
+
+usage: subtree_sync.sh <command> [<args>]
+
+commands:
+    subtree-push           Push changes from rust-lang/rust back to rustfmt.
+"
+}
+
+function main() {
+    local COMMAND=$1
+    local COMMIT_AUTHOR="rustfmt bot <rustfmt@sync.bot>"
+
+    case COMMAND in
+        subtree-push)
+            install_latest_nightly
+            run_rustfmt_subtree_push $COMMIT_AUTHOR
+            ;;
+        *)
+            print_help
+            ;;
+    esac
+}
+
+main $@