diff --git a/lib/classes/output/mustache_user_date_helper.php b/lib/classes/output/mustache_user_date_helper.php
new file mode 100644
index 0000000000000..2e6815682b6d5
--- /dev/null
+++ b/lib/classes/output/mustache_user_date_helper.php
@@ -0,0 +1,62 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Mustache helper that will convert a timestamp to a date string.
+ *
+ * @package    core
+ * @category   output
+ * @copyright  2017 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core\output;
+
+defined('MOODLE_INTERNAL') || die();
+
+use Mustache_LambdaHelper;
+
+/**
+ * Mustache helper that will convert a timestamp to a date string.
+ *
+ * @copyright  2017 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class mustache_user_date_helper {
+
+    /**
+     * Read a timestamp and format from the string.
+     *
+     * {{#shortentext}} 1487655635, Y-M-D {{/shortentext}}
+     *
+     * Both args are required. The timestamp must come first.
+     *
+     * @param string $args The text to parse for arguments.
+     * @param Mustache_LambdaHelper $helper Used to render nested mustache variables.
+     * @return string
+     */
+    public function transform($args, Mustache_LambdaHelper $helper) {
+        // Split the text into an array of variables.
+        list($timestamp, $format) = explode(',', $args, 2);
+        $timestamp = trim($timestamp);
+        $format = trim($format);
+
+        $timestamp = $helper->render($timestamp);
+        $format = $helper->render($format);
+
+        return userdate($timestamp, $format);
+    }
+}
diff --git a/lib/outputrenderers.php b/lib/outputrenderers.php
index 550b09887a1a1..27e15100f27fa 100644
--- a/lib/outputrenderers.php
+++ b/lib/outputrenderers.php
@@ -91,6 +91,7 @@ protected function get_mustache() {
             $quotehelper = new \core\output\mustache_quote_helper();
             $jshelper = new \core\output\mustache_javascript_helper($this->page->requires);
             $pixhelper = new \core\output\mustache_pix_helper($this);
+            $userdatehelper = new \core\output\mustache_user_date_helper();
 
             // We only expose the variables that are exposed to JS templates.
             $safeconfig = $this->page->requires->get_config_for_javascript($this->page, $this);
@@ -99,7 +100,8 @@ protected function get_mustache() {
                              'str' => array($stringhelper, 'str'),
                              'quote' => array($quotehelper, 'quote'),
                              'js' => array($jshelper, 'help'),
-                             'pix' => array($pixhelper, 'pix'));
+                             'pix' => array($pixhelper, 'pix'),
+                             'userdate' => array($userdatehelper, 'transform'));
 
             $this->mustache = new Mustache_Engine(array(
                 'cache' => $cachedir,