diff --git a/scripts/dev/format_pull_request.php b/scripts/dev/format_pull_request.php
new file mode 100644
index 0000000000000..7b2e23e5ceb79
--- /dev/null
+++ b/scripts/dev/format_pull_request.php
@@ -0,0 +1,86 @@
+<?php
+
+declare(strict_types=1);
+error_reporting(E_ALL);
+set_error_handler(function ($errno, $errstr, $errfile, $errline) {
+    if (error_reporting() & $errno) {
+        throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
+    }
+});
+$force = array_search('--force', $argv, true);
+if ($force !== false) {
+    unset($argv[$force]);
+    $force = true;
+    $argv = array_values($argv);
+    $argc = count($argv);
+}
+if ($argc !== 2) {
+    ob_start();
+    echo "Usage: php {$argv[0]} [diff-uri]\n";
+    echo "example:\nphp {$argv[0]} " . escapeshellarg('https://github.com/php/php-src/pull/13401.diff') . "\n";
+    fwrite(STDERR, ob_get_clean());
+    exit(1);
+}
+chdir(__DIR__ . '/../../'); // php-src root
+if (!$force) {
+    $gitStatus = null;
+    system('git diff --quiet --exit-code', $gitStatus);
+    if ($gitStatus !== 0) {
+        fwrite(STDERR, "Error: Working directory is not clean according to 'git diff'\n");
+        fwrite(STDERR, "commit your stuff -or- run 'git reset --hard' and try again\n");
+        exit(1);
+    }
+    unset($gitStatus);
+}
+//
+$diff = file_get_contents($argv[1]);
+$diffFileHandle = tmpfile();
+fwrite($diffFileHandle, $diff);
+$diffFilePath = stream_get_meta_data($diffFileHandle)['uri'];
+passthru("git apply " . escapeshellarg($diffFilePath), $ret);
+if ($ret !== 0) {
+    fwrite(STDERR, "Error: git apply failed with exit code {$ret}\n");
+    if (!$force) {
+        passthru('git reset --hard');
+    }
+    exit(1);
+}
+// commit
+passthru('git commit -a --message=clangformat --quiet', $ret);
+if ($ret !== 0) {
+    fwrite(STDERR, "Error: git commit failed with exit code {$ret}\n");
+    if (!$force) {
+        passthru('git reset --hard');
+    }
+    exit(1);
+}
+$clangFormatOptions = array(
+    // tests on ext/standard/array.c indicate that the clang-format
+    // preset that most closely resembles the php-src coding style is WebKit
+    'BasedOnStyle' => 'WebKit',
+    'UseTab' => 'ForIndentation',
+    // clang-format's support for tabs isn't great, and we have to say "4 spaces" to get 1 tab
+    'IndentWidth' => 4,
+    'TabWidth' => 4,
+);
+$cmd = array(
+    'git diff -U0 --no-color --relative HEAD^ |',
+    'clang-format-diff -i -p1 -style=' . escapeshellarg(json_encode($clangFormatOptions)),
+    '-iregex=' . escapeshellarg('.*\.(c|cc|cpp|c\+\+|cxx|h|hh|hpp|h\+\+|h)$'),
+);
+$cmd = implode(' ', $cmd);
+passthru($cmd, $ret);
+if ($ret !== 0) {
+    fwrite(STDERR, "Error: clang-format-diff failed with exit code {$ret}\n");
+    fwrite(STDERR, "cmd:\n{$cmd}\n");
+    if (!$force) {
+        // remove last commit and reset
+        passthru('git reset --hard HEAD^ --quiet');
+    }
+    exit(1);
+}
+passthru('git diff');
+if (!$force) {
+    // remove last commit and reset
+    passthru('git reset --hard HEAD^ --quiet');
+}