diff --git a/cgit.h b/cgit.h
index a0cf5e9..ddd2ccb 100644
--- a/cgit.h
+++ b/cgit.h
@@ -25,6 +25,7 @@
 #include <utf8.h>
 #include <notes.h>
 #include <graph.h>
+#include <inttypes.h>
 
 /* Add isgraph(x) to Git's sane ctype support (see git-compat-util.h) */
 #undef isgraph
diff --git a/cgit.js b/cgit.js
index b35e0bc..df3ad4e 100644
--- a/cgit.js
+++ b/cgit.js
@@ -5,3 +5,64 @@
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
+
+(function () {
+
+/* This follows the logic and suffixes used in ui-shared.c */
+
+var age_classes = [ "age-mins", "age-hours", "age-days",    "age-weeks",    "age-months",    "age-years" ];
+var age_suffix =  [ "min.",     "hours",     "days",        "weeks",        "months",        "years",         "years" ];
+var age_next =    [ 60,         3600,        24 * 3600,     7 * 24 * 3600,  30 * 24 * 3600,  365 * 24 * 3600, 365 * 24 * 3600 ];
+var age_limit =   [ 7200,       24 * 7200,   7 * 24 * 7200, 30 * 24 * 7200, 365 * 25 * 7200, 365 * 25 * 7200 ];
+var update_next = [ 10,         5 * 60,      1800,          24 * 3600,      24 * 3600,       24 * 3600,       24 * 3600 ];
+
+function render_age(e, age) {
+	var t, n;
+
+	for (n = 0; n < age_classes.length; n++)
+		if (age < age_limit[n])
+			break;
+
+	t = Math.round(age / age_next[n]) + " " + age_suffix[n];
+
+	if (e.textContent != t) {
+		e.textContent = t;
+		if (n == age_classes.length)
+			n--;
+		if (e.className != age_classes[n])
+			e.className = age_classes[n];
+	}
+}
+
+function aging() {
+	var n, next = 24 * 3600,
+	    now_ut = Math.round((new Date().getTime() / 1000));
+
+	for (n = 0; n < age_classes.length; n++) {
+		var m, elems = document.getElementsByClassName(age_classes[n]);
+
+		if (elems.length && update_next[n] < next)
+			next = update_next[n];
+
+		for (m = 0; m < elems.length; m++) {
+			var age = now_ut - elems[m].getAttribute("data-ut");
+
+			render_age(elems[m], age);
+		}
+	}
+
+	/*
+	 * We only need to come back when the age might have changed.
+	 * Eg, if everything is counted in hours already, once per
+	 * 5 minutes is accurate enough.
+	 */
+
+	window.setTimeout(aging, next * 1000);
+}
+
+document.addEventListener("DOMContentLoaded", function() {
+	/* we can do the aging on DOM content load since no layout dependency */
+	aging();
+}, false);
+
+})();
diff --git a/ui-shared.c b/ui-shared.c
index c50b3e6..11aed19 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -673,7 +673,7 @@ const struct date_mode *cgit_date_mode(enum date_mode_type type)
 static void print_rel_date(time_t t, int tz, double value,
 	const char *class, const char *suffix)
 {
-	htmlf("<span class='%s' title='", class);
+	htmlf("<span class='%s' data-ut='%" PRIu64 "' title='", class, (uint64_t)t);
 	html_attr(show_date(t, tz, cgit_date_mode(DATE_ISO8601)));
 	htmlf("'>%.0f %s</span>", value, suffix);
 }