diff --git a/admin/README.md b/admin/README.md
index 958004b41967..a4048bf59152 100644
--- a/admin/README.md
+++ b/admin/README.md
@@ -65,6 +65,10 @@ are used as part of that process:
     of the version's upgrade guide with the project space files changed since
     the last release.
     Usage: `php admin/update-upgrade-guide.php <version> [--dry-run]`
+-   **sync-release-branches.php** checks out the target branch and merges
+    upstream and the source branch into it, as done at several points of the
+    release process. Without `--push`, the result is left unpushed for review.
+    Usage: `php admin/sync-release-branches.php <target> <source> [--push]`
 
 ## Other Stuff
 
diff --git a/admin/RELEASE.md b/admin/RELEASE.md
index 8fa117e4f8a4..75f2a0fbf35a 100644
--- a/admin/RELEASE.md
+++ b/admin/RELEASE.md
@@ -1,11 +1,10 @@
 # Release Process
 
-> Documentation guide based on the releases of `4.0.5` and `4.1.0` on January 31, 2021.
+> Documentation guide based on the releases of `4.0.5` and `4.1.0` on January 31, 2021 (MGatner)
 >
-> Updated for `4.5.0` on April 7, 2024.
-> Updated for `4.6.0` on January 19, 2025.
->
-> -MGatner, kenjis
+> Updated for `4.5.0` on April 7, 2024 (kenjis)
+> Updated for `4.6.0` on January 19, 2025 (paulbalandan)
+> Updated for `4.7.5` on July 8, 2026 (paulbalandan)
 
 ## Notation
 
@@ -24,11 +23,7 @@ merging will take time.
 
 * [ ] Merge `develop` into `4.y`:
     ```console
-    git fetch upstream
-    git switch 4.y
-    git merge upstream/4.y
-    git merge upstream/develop
-    git push upstream HEAD
+    php admin/sync-release-branches.php 4.y develop --push
     ```
 
 ## [Minor version only] Merge minor version branch into `develop`
@@ -183,19 +178,11 @@ existing content.
   * If it fails, fix the cause and re-run it via "Run workflow" with the tag `v4.x.x`.
 * [ ] Fast-forward `develop` branch to catch the merge commit from `master`
     ```console
-    git fetch upstream
-    git checkout develop
-    git merge upstream/develop
-    git merge upstream/master
-    git push upstream HEAD
+    php admin/sync-release-branches.php develop master --push
     ```
 * [ ] Update the next minor version branch `4.y`:
     ```console
-    git fetch upstream
-    git switch 4.y
-    git merge upstream/4.y
-    git merge upstream/develop
-    git push upstream HEAD
+    php admin/sync-release-branches.php 4.y develop --push
     ```
 * [ ] [Minor version only] Create the new next minor version branch `4.z`:
     ```console
diff --git a/admin/sync-release-branches.php b/admin/sync-release-branches.php
new file mode 100644
index 000000000000..4f82a424bc65
--- /dev/null
+++ b/admin/sync-release-branches.php
@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Syncs the target branch with upstream and merges in the given source
+ * branch, as done at several points of the release process.
+ *
+ * Usage: php admin/sync-release-branches.php <target> <source> [--push]
+ */
+function run_command(string $command): void
+{
+    echo sprintf("$ %s\n", $command);
+    system($command, $exitCode);
+
+    if ($exitCode !== 0) {
+        exit($exitCode);
+    }
+}
+
+function merge_branch(string $ref): void
+{
+    echo sprintf("$ git merge %s\n", $ref);
+    system(sprintf('git merge %s', escapeshellarg($ref)), $exitCode);
+
+    if ($exitCode !== 0) {
+        echo sprintf("\nMerging %s failed. Resolve the conflicts and run \"git merge --continue\",\n", $ref);
+        echo "then push with \"git push upstream HEAD\".\n";
+
+        exit(1);
+    }
+}
+
+chdir(__DIR__ . '/..');
+
+$args    = array_slice($argv, 1);
+$options = array_values(array_filter($args, static fn (string $arg): bool => str_starts_with($arg, '--')));
+$params  = array_values(array_diff($args, $options));
+
+$isBranch = static fn (string $name): bool => preg_match('/\A(?:develop|master|\d+\.\d+)\z/', $name) === 1;
+
+if (
+    count($params) !== 2
+    || ! $isBranch($params[0])
+    || ! $isBranch($params[1])
+    || $params[0] === $params[1]
+    || array_diff($options, ['--push']) !== []
+) {
+    echo sprintf("Usage: php %s <target> <source> [--push]\n", $argv[0]);
+    echo sprintf("E.g.,: php %s 4.8 develop --push    # merges develop into 4.8\n", $argv[0]);
+    echo sprintf("       php %s develop master --push # merges master into develop\n", $argv[0]);
+    echo "Checks out <target>, merges upstream/<target> and then upstream/<source> into it.\n";
+    echo "Without --push, the result is left unpushed for review.\n";
+
+    exit(1);
+}
+
+[$target, $source] = $params;
+$push              = in_array('--push', $options, true);
+
+exec('git remote get-url upstream 2>&1', $remoteOutput, $exitCode);
+
+if ($exitCode !== 0) {
+    echo "The \"upstream\" remote is not configured.\n";
+
+    exit(1);
+}
+
+exec('git status --porcelain 2>&1', $statusOutput, $exitCode);
+
+if ($exitCode !== 0 || $statusOutput !== []) {
+    echo "The working tree is not clean. Commit or stash your changes first.\n";
+
+    exit(1);
+}
+
+run_command('git fetch upstream');
+
+exec(sprintf('git rev-parse --verify --quiet refs/heads/%s 2>&1', escapeshellarg($target)), $verifyOutput, $exitCode);
+
+if ($exitCode === 0) {
+    run_command(sprintf('git switch %s', escapeshellarg($target)));
+} else {
+    run_command(sprintf('git switch -c %s upstream/%s', escapeshellarg($target), escapeshellarg($target)));
+}
+
+merge_branch("upstream/{$target}");
+merge_branch("upstream/{$source}");
+
+if ($push) {
+    run_command('git push upstream HEAD');
+
+    echo sprintf("Merged upstream/%s into %s and pushed to upstream.\n", $source, $target);
+} else {
+    echo sprintf("Merged upstream/%s into %s. Review the result, then run \"git push upstream HEAD\".\n", $source, $target);
+}
diff --git a/tests/system/AutoReview/SyncReleaseBranchesTest.php b/tests/system/AutoReview/SyncReleaseBranchesTest.php
new file mode 100644
index 000000000000..26d90c4b1592
--- /dev/null
+++ b/tests/system/AutoReview/SyncReleaseBranchesTest.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\AutoReview;
+
+use PHPUnit\Framework\Attributes\CoversNothing;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * The successful path switches branches and merges, so only the argument
+ * validation is exercised here.
+ *
+ * @internal
+ */
+#[CoversNothing]
+#[Group('AutoReview')]
+final class SyncReleaseBranchesTest extends TestCase
+{
+    #[DataProvider('provideUsageErrors')]
+    public function testUsageErrors(string $arguments): void
+    {
+        exec(sprintf('php ./admin/sync-release-branches.php %s 2>&1', $arguments), $output, $exitCode);
+
+        $this->assertSame(1, $exitCode);
+        $this->assertStringContainsString('Usage:', implode("\n", $output));
+    }
+
+    /**
+     * @return iterable<string, array{0: string}>
+     */
+    public static function provideUsageErrors(): iterable
+    {
+        yield 'no arguments' => [''];
+
+        yield 'missing source' => ['4.8'];
+
+        yield 'invalid branch' => ['release-4.8.0 develop'];
+
+        yield 'invalid source' => ['4.8 upstream/develop'];
+
+        yield 'same branch and source' => ['develop develop'];
+
+        yield 'unknown option' => ['4.8 develop --force'];
+    }
+}