diff --git a/mercurial/templatefilters.py b/mercurial/templatefilters.py
--- a/mercurial/templatefilters.py
+++ b/mercurial/templatefilters.py
@@ -206,6 +206,37 @@
     """
     return util.datestr(text, '%Y-%m-%d %H:%M:%S %1%2')
 
+@templatefilter('reldate')
+def reldate(text):
+    """Date. Returns how long ago the date was in relative human-readable form,
+    e.g. "3 hours ago".
+
+    If the date is more than a week old, returns an ISO-like string in the
+    format "%Y-%m-%d".
+    """
+    # From https://stackoverflow.com/a/5164027/303833
+    date = util.hgdatetopython(text)
+    delta = util.hgdatetopython(util.makedate()) - date
+    secs = delta.seconds
+    if delta.days > 7 or delta.days < 0:
+        return date.strftime('%Y-%m-%d')
+    elif delta.days == 1:
+        return '1 day ago'
+    elif delta.days > 1:
+        return '%d days ago' % delta.days
+    elif secs <= 1:
+        return 'just now'
+    elif secs < 60:
+        return '%d seconds ago' % secs
+    elif secs < 120:
+        return '1 minute ago'
+    elif secs < 3600:
+        return '%d minutes ago' % (secs / 60)
+    elif secs < 7200:
+        return '1 hour ago'
+    else:
+        return '%d hours ago' % (secs / 3600)
+
 def indent(text, prefix):
     '''indent each non-empty line of text after first with prefix.'''
     lines = text.splitlines()
diff --git a/tests/test-command-template.t b/tests/test-command-template.t
--- a/tests/test-command-template.t
+++ b/tests/test-command-template.t
@@ -2091,6 +2091,27 @@
   1970-01-13 17:33:20 +0000
   1970-01-12 13:46:40 +0000
 
+  $ cat > oldtime.py <<EOF
+  > import time
+  > def oldtime():
+  >   return 1500500
+  > time.time = oldtime
+  > EOF
+  $ cp $HGRCPATH $HGRCPATH.bak
+  $ echo "[extensions]" >> $HGRCPATH
+  $ echo "loop=`pwd`/oldtime.py" >> $HGRCPATH
+  $ hg log --template '{date|reldate}\n'
+  2020-01-01
+  5 days ago
+  8 minutes ago
+  8 minutes ago
+  1 day ago
+  2 days ago
+  3 days ago
+  4 days ago
+  5 days ago
+  $ mv $HGRCPATH.bak $HGRCPATH
+
   $ hg log --template '{date|rfc822date}\n'
   Wed, 01 Jan 2020 10:01:00 +0000
   Mon, 12 Jan 1970 13:46:40 +0000