diff --git a/public/javascripts/jquery.instructure_date_and_time.js b/public/javascripts/jquery.instructure_date_and_time.js
index 345076c56dc..ebb96f4b176 100644
--- a/public/javascripts/jquery.instructure_date_and_time.js
+++ b/public/javascripts/jquery.instructure_date_and_time.js
@@ -133,7 +133,7 @@ var speakMessage = function ($this, message) {
     if (date == null) return "";
     var timezone = options && options.timezone;
     var format = options && options.format;
-    format = (format !== 'medium') && $.sameYear(date, new Date()) ? '%b %-d' : '%b %-d, %Y';
+    format = (format !== 'medium') && $.sameYear(date, new Date()) ? 'date.formats.short' : 'date.formats.medium';
     if (typeof timezone == 'string' || timezone instanceof String) {
       return tz.format(date, format, timezone) || '';
     } else {
@@ -144,13 +144,10 @@ var speakMessage = function ($this, message) {
   $.timeString = function(date, options) {
     if (date == null) return "";
     var timezone = options && options.timezone;
-    // lookup format according to locale, and then turn %l or %k into %-l or
-    // %-k, respectively, to avoid extra unnecessary space characters
-    var fmt = I18n.t("#time.formats.tiny").replace(/^%([kl])/, "%-$1");
     if (typeof timezone == 'string' || timezone instanceof String) {
-      return tz.format(date, fmt, timezone) || '';
+      return tz.format(date, 'time.formats.tiny', timezone) || '';
     } else {
-      return tz.format(date, fmt) || '';
+      return tz.format(date, 'time.formats.tiny') || '';
     }
   };
   $.datetimeString = function(datetime, options) {
diff --git a/public/javascripts/timezone_core.js b/public/javascripts/timezone_core.js
index 9e2e07f566c..cde2f4cef33 100644
--- a/public/javascripts/timezone_core.js
+++ b/public/javascripts/timezone_core.js
@@ -2,8 +2,9 @@ define([
   "jquery",
   "underscore",
   "require",
-  "vendor/timezone"
-], function($, _, require, tz) {
+  "vendor/timezone",
+  "i18nObj"
+], function($, _, require, tz, I18n) {
   // start with the bare vendor-provided tz() function
   var _tz = tz;
   var _preloadedData = {};
@@ -44,6 +45,25 @@ define([
       var datetime = tz.parse(value);
       if (datetime == null) return null;
 
+      // translate recognized 'date.formats.*' and 'time.formats.*' to
+      // appropriate format strings according to locale.
+      if (format.match(/^(date|time)\.formats\./)) {
+        var locale_format = I18n.lookup(format);
+        if (locale_format) {
+          // in the process, turn %l, %k, and %e into %-l, %-k, and %-e
+          // (respectively) to avoid extra unnecessary space characters
+          //
+          // javascript doesn't have lookbehind, so do the fixing on the reversed
+          // string so we can use lookahead instead. the funky '(%%)*(?!%)' pattern
+          // in all the regexes is to make sure we match (once unreversed), e.g.,
+          // both %l and %%%l (literal-% + %l) but not %%l (literal-% + l).
+          format = locale_format.
+            split("").reverse().join("").
+            replace(/([lke])(?=%(%%)*(?!%))/, '$1-').
+            split("").reverse().join("");
+        }
+      }
+
       // some locales may not (according to bigeasy's localization files) use
       // an am/pm distinction, but could then be incorrectly used with 12-hour
       // format strings (e.g. %l:%M%P), whether by erroneous format strings in
@@ -51,12 +71,8 @@ define([
       // result, you might get 3am and 3pm both formatting to the same value.
       // to prevent this, 12-hour indicators with an am/pm indicator should be
       // promoted to the equivalent 24-hour indicator when the locale defines
-      // %P as an empty string.
-
-      // javascript doesn't have lookbehind, so do the fixing on the reversed
-      // string so we can use lookahead instead. the funky '(%%)*(?!%)' pattern
-      // in all the regexes is to make sure we match (once unreversed), e.g.,
-      // both %l and %%%l (literal-% + %l) but not %%l (literal-% + l).
+      // %P as an empty string. ("reverse, look-ahead, reverse" pattern for
+      // same reason as above)
       format = format.split("").reverse().join("");
       if (_tz(datetime, '%P') === '' &&
           ((format.match(/[lI][-_]?%(%%)*(?!%)/) &&
diff --git a/spec/coffeescripts/helpers/I18nStubber.coffee b/spec/coffeescripts/helpers/I18nStubber.coffee
new file mode 100644
index 00000000000..72784f55d65
--- /dev/null
+++ b/spec/coffeescripts/helpers/I18nStubber.coffee
@@ -0,0 +1,33 @@
+define ['i18nObj'], (I18n) ->
+  frames = []
+
+  I18nStubber =
+    pushFrame: ->
+      frames.push
+        locale: I18n.locale
+        translations: I18n.translations
+      I18n.translations = {'en': {}}
+
+    popFrame: ->
+      throw 'I18nStubber: pop without a stored frame' unless frames.length
+      {locale, translations} = frames.pop()
+      I18n.locale = locale
+      I18n.translations = translations
+
+    stub: (locale, translations) ->
+      throw 'I18nStubber: stub without a stored frame' unless frames.length
+      scope = I18n.translations
+      scope[locale] = {} unless scope[locale]
+      locale = scope[locale]
+      for key, value of translations
+        scope = locale
+        parts = key.split('.')
+        last = parts.pop()
+        for part in parts
+          scope[part] = {} unless scope[part]
+          scope = scope[part]
+        scope[last] = value
+
+    setLocale: (locale) ->
+      throw 'I18nStubber: setLocale without a stored frame' unless frames.length
+      I18n.locale = locale
diff --git a/spec/coffeescripts/instructureDateAndTimeSpec.coffee b/spec/coffeescripts/instructureDateAndTimeSpec.coffee
index b9ea43fec81..1c82ea30cbb 100644
--- a/spec/coffeescripts/instructureDateAndTimeSpec.coffee
+++ b/spec/coffeescripts/instructureDateAndTimeSpec.coffee
@@ -4,9 +4,9 @@ define [
   'vendor/timezone/America/Detroit'
   'vendor/timezone/America/Juneau'
   'vendor/timezone/pt_PT'
-  'i18nObj'
+  'helpers/I18nStubber'
   'jquery.instructure_date_and_time'
-], ($, tz, detroit, juneau, portuguese, I18n) ->
+], ($, tz, detroit, juneau, portuguese, I18nStubber) ->
   module 'fudgeDateForProfileTimezone',
     setup: ->
       @snapshot = tz.snapshot()
@@ -137,65 +137,73 @@ define [
     ok !$.midnight(date3)
 
   module 'dateString',
-    setup: -> @snapshot = tz.snapshot()
-    teardown: -> tz.restore(@snapshot)
+    setup: ->
+      @snapshot = tz.snapshot()
+      I18nStubber.pushFrame()
+
+    teardown: ->
+      tz.restore(@snapshot)
+      I18nStubber.popFrame()
 
   test 'should format in profile timezone', ->
+    I18nStubber.stub 'en', 'date.formats.medium': "%b %-d, %Y"
     tz.changeZone(detroit, 'America/Detroit')
     equal $.dateString(new Date(0)), 'Dec 31, 1969'
 
   module 'timeString',
     setup: ->
       @snapshot = tz.snapshot()
-      @localeWas = I18n.locale
-      @translationsWas = I18n.translations
-      I18n.translations =
-        'en': {'time': {'formats': {'tiny': "%l:%M%P"}}}
-        'en-GB': {'time': {'formats': {'tiny': "%k:%M"}}}
+      I18nStubber.pushFrame()
+
     teardown: ->
       tz.restore(@snapshot)
-      I18n.locale = @localeWas
-      I18n.translations = @translationsWas
+      I18nStubber.popFrame()
 
   test 'should format in profile timezone', ->
+    I18nStubber.stub 'en', 'time.formats.tiny': "%l:%M%P"
     tz.changeZone(detroit, 'America/Detroit')
     equal $.timeString(new Date(0)), '7:00pm'
 
   test 'should format according to profile locale', ->
-    I18n.locale = 'en-GB'
+    I18nStubber.setLocale 'en-GB'
+    I18nStubber.stub 'en-GB', 'time.formats.tiny': "%k:%M"
     equal $.timeString(new Date(46800000)), '13:00'
 
   module 'datetimeString',
     setup: ->
       @snapshot = tz.snapshot()
-      @localeWas = I18n.locale
-      @translationsWas = I18n.translations
-      I18n.translations =
-        'en': {'time': {'formats': {'tiny': "%l:%M%P"}}}
-        'pt': {'time': {'event': "%{date} em %{time}"}}
+      I18nStubber.pushFrame()
+
     teardown: ->
       tz.restore(@snapshot)
-      I18n.locale = @localeWas
-      I18n.translations = @translationsWas
+      I18nStubber.popFrame()
 
   test 'should format in profile timezone', ->
     tz.changeZone(detroit, 'America/Detroit')
+    I18nStubber.stub 'en',
+      'date.formats.medium': "%b %-d, %Y"
+      'time.formats.tiny': "%l:%M%P"
+      'time.event': "%{date} at %{time}"
     equal $.datetimeString(new Date(0)), 'Dec 31, 1969 at 7:00pm'
 
   test 'should translate into the profile locale', ->
     tz.changeLocale(portuguese, 'pt_PT')
-    I18n.locale = 'pt'
-    equal $.datetimeString('1970-01-01 15:00:00Z'), "Jan 1, 1970 em 15:00"
+    I18nStubber.setLocale 'pt'
+    I18nStubber.stub 'pt',
+      'date.formats.medium': "%-d %b %Y"
+      'time.formats.tiny': "%k:%M"
+      'time.event': "%{date} em %{time}"
+    equal $.datetimeString('1970-01-01 15:00:00Z'), "1 Jan 1970 em 15:00"
 
   # TODO: remove these second argument specs once the pickers know how to parse
   # localized datetimes
   test 'should not localize if second argument is false', ->
     tz.changeLocale(portuguese, 'pt_PT')
-    I18n.locale = 'pt'
+    I18nStubber.setLocale 'pt'
     equal $.datetimeString('1970-01-01 15:00:00Z', {localized: false}), "Jan 1, 1970 at 3:00pm"
 
   test 'should still apply profile timezone when second argument is false', ->
     tz.changeZone(detroit, 'America/Detroit')
     tz.changeLocale(portuguese, 'pt_PT')
-    I18n.locale = 'pt'
+    I18nStubber.setLocale 'pt'
     equal $.datetimeString(new Date(0), {localized: false}), 'Dec 31, 1969 at 7:00pm'
diff --git a/spec/coffeescripts/timezoneSpec.coffee b/spec/coffeescripts/timezoneSpec.coffee
index bc5719683ff..c178e7cf5c4 100644
--- a/spec/coffeescripts/timezoneSpec.coffee
+++ b/spec/coffeescripts/timezoneSpec.coffee
@@ -3,15 +3,20 @@ define [
   'vendor/timezone/America/Detroit'
   'vendor/timezone/fr_FR'
   'vendor/timezone/pt_PT'
-], (tz, detroit, french, portuguese)->
+  'helpers/I18nStubber'
+], (tz, detroit, french, portuguese, I18nStubber)->
+
   module 'timezone',
     setup: ->
       @snapshot = tz.snapshot()
+      I18nStubber.pushFrame()
 
     teardown: ->
       tz.restore(@snapshot)
+      I18nStubber.popFrame()
 
   moonwalk = new Date(Date.UTC(1969, 6, 21, 2, 56))
+  epoch = new Date(Date.UTC(1970, 0, 1, 0, 0))
 
   test 'parse(valid datetime string)', ->
     equal +tz.parse(moonwalk.toISOString()), +moonwalk
@@ -68,6 +73,32 @@ define [
     equal tz.format(time, '%I%P'), "15"
     equal tz.format(time, '%r'), "15:00:00"
 
+  test "format() should recognize date.formats.*", ->
+    I18nStubber.stub 'en', 'date.formats.short': '%b %-d'
+    equal tz.format(moonwalk, 'date.formats.short'), "Jul 21"
+
+  test "format() should recognize time.formats.*", ->
+    I18nStubber.stub 'en', 'time.formats.tiny': '%-l:%M%P'
+    equal tz.format(epoch, 'time.formats.tiny'), "12:00am"
+
+  test "format() should localize when given a localization key", ->
+    tz.changeLocale(french, 'fr_FR')
+    I18nStubber.setLocale 'fr_FR'
+    I18nStubber.stub 'fr_FR', 'date.formats.full': '%-d %b %Y %-l:%M%P'
+    equal tz.format(moonwalk, 'date.formats.full'), "21 juil. 1969 2:56"
+
+  test "format() should automatically convert %l to %-l when given a localization key", ->
+    I18nStubber.stub 'en', 'time.formats.tiny': '%l:%M%P'
+    equal tz.format(moonwalk, 'time.formats.tiny'), "2:56am"
+
+  test "format() should automatically convert %k to %-k when given a localization key", ->
+    I18nStubber.stub 'en', 'time.formats.tiny': '%k:%M'
+    equal tz.format(moonwalk, 'time.formats.tiny'), "2:56"
+
+  test "format() should automatically convert %e to %-e when given a localization key", ->
+    I18nStubber.stub 'en', 'date.formats.short': '%b %e'
+    equal tz.format(epoch, 'date.formats.short'), "Jan 1"
+
   test 'shift() should adjust the date as appropriate', ->
     equal +tz.shift(moonwalk, '-1 day'), moonwalk - 86400000