new file mode 100644
--- /dev/null
+++ b/mobile/android/base/java/org/mozilla/gecko/home/activitystream/DurationFormat.java
@@ -0,0 +1,60 @@
+/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+package org.mozilla.gecko.home.activitystream;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.text.format.DateUtils;
+
+import org.mozilla.gecko.R;
+
+import java.text.DateFormat;
+
+public class DurationFormat {
+
+    /**
+     * Format a date as time duration since that date. I.e. for a given input time, return
+     * "now" for recent times, strings such as "1m", "3h", "4d", "2w", for intermediate durations,
+     * or an absolute date (12 Jan 2015) for dates more than 4 weeks ago.
+     *
+     * Will also return "now" for dates in the future.
+     */
+    public static String formatDurationSince(final Context context, final long date) {
+        final Resources resources = context.getResources();
+
+        final long duration = System.currentTimeMillis() - date;
+
+        final String formatString;
+        final long formatTime;
+
+        if (duration < DateUtils.MINUTE_IN_MILLIS) {
+            // Less than one minute ago -> now
+            // This case also covers illogical (negative) durations, maybe that can
+            // happen with sync?
+            return resources.getString(R.string.duration_now);
+        } else if (duration < DateUtils.HOUR_IN_MILLIS) {
+            // Less than 1 hour ago -> "5m"
+            formatString = resources.getString(R.string.duration_minutes);
+            formatTime = (duration / DateUtils.MINUTE_IN_MILLIS);
+        } else if (duration < DateUtils.DAY_IN_MILLIS) {
+            // Less than 1 day ago -> "5h"
+            formatString = resources.getString(R.string.duration_hours);
+            formatTime = (duration / DateUtils.HOUR_IN_MILLIS);
+        } else if (duration < DateUtils.WEEK_IN_MILLIS) {
+            // Less than 1 week ago -> "5d"
+            formatString = resources.getString(R.string.duration_days);
+            formatTime = (duration / DateUtils.DAY_IN_MILLIS);
+        } else if (duration < 4 * DateUtils.WEEK_IN_MILLIS) {
+            // Less than 4 weeks ago -> "3w"
+            formatString = resources.getString(R.string.duration_weeks);
+            formatTime = (duration / DateUtils.WEEK_IN_MILLIS);
+        } else {
+            // Otherwise: show the date
+            return DateFormat.getDateInstance(DateFormat.SHORT).format(date);
+        }
+
+        return String.format(formatString, formatTime);
+    }
+}

--- a/mobile/android/base/locales/en-US/android_strings.dtd
+++ b/mobile/android/base/locales/en-US/android_strings.dtd
@@ -826,8 +826,13 @@ just addresses the organization to follo
 <!ENTITY helper_first_offline_bookmark_title "Read offline">
 <!ENTITY helper_first_offline_bookmark_message "Find your Reader View items in Bookmarks, even offline.">
 <!ENTITY helper_first_offline_bookmark_button "Go to Bookmarks">
 
 <!ENTITY helper_triple_readerview_open_title "Available offline">
 <!ENTITY helper_triple_readerview_open_message "Bookmark Reader View items to read them offline.">
 <!ENTITY helper_triple_readerview_open_button "Add to Bookmarks">
 
+<!ENTITY duration_now "now">
+<!ENTITY duration_minutes "&formatD;m">
+<!ENTITY duration_hours "&formatD;h">
+<!ENTITY duration_days "&formatD;d">
+<!ENTITY duration_weeks "&formatD;w">

--- a/mobile/android/base/moz.build
+++ b/mobile/android/base/moz.build
@@ -434,16 +434,17 @@ gbjar.sources += ['java/org/mozilla/geck
     'GeckoProfilesProvider.java',
     'GeckoUpdateReceiver.java',
     'GlobalHistory.java',
     'GuestSession.java',
     'health/HealthRecorder.java',
     'health/SessionInformation.java',
     'health/StubbedHealthRecorder.java',
     'home/activitystream/ActivityStream.java',
+    'home/activitystream/DurationFormat.java',
     'home/BookmarkFolderView.java',
     'home/BookmarkScreenshotRow.java',
     'home/BookmarksListAdapter.java',
     'home/BookmarksListView.java',
     'home/BookmarksPanel.java',
     'home/BrowserSearch.java',
     'home/ClientsAdapter.java',
     'home/CombinedHistoryAdapter.java',

--- a/mobile/android/base/strings.xml.in
+++ b/mobile/android/base/strings.xml.in
@@ -629,9 +629,14 @@
   <string name="helper_first_offline_bookmark_title">&helper_first_offline_bookmark_title;</string>
   <string name="helper_first_offline_bookmark_message">&helper_first_offline_bookmark_message;</string>
   <string name="helper_first_offline_bookmark_button">&helper_first_offline_bookmark_button;</string>
 
   <string name="helper_triple_readerview_open_title">&helper_triple_readerview_open_title;</string>
   <string name="helper_triple_readerview_open_message">&helper_triple_readerview_open_message;</string>
   <string name="helper_triple_readerview_open_button">&helper_triple_readerview_open_button;</string>
 
+  <string name="duration_now">&duration_now;</string>
+  <string name="duration_minutes">&duration_minutes;</string>
+  <string name="duration_hours">&duration_hours;</string>
+  <string name="duration_days">&duration_days;</string>
+  <string name="duration_weeks">&duration_weeks;</string>
 </resources>