diff --git a/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php b/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php
index 7added162f..4f65202a2c 100644
--- a/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php
+++ b/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php
@@ -1,499 +1,503 @@
 <?php
 
 final class PhabricatorCalendarEventSearchEngine
   extends PhabricatorApplicationSearchEngine {
 
   private $calendarYear;
   private $calendarMonth;
   private $calendarDay;
 
   public function getResultTypeDescription() {
     return pht('Calendar Events');
   }
 
   public function getApplicationClassName() {
     return 'PhabricatorCalendarApplication';
   }
 
   public function buildSavedQueryFromRequest(AphrontRequest $request) {
     $saved = new PhabricatorSavedQuery();
 
     $saved->setParameter(
       'rangeStart',
       $this->readDateFromRequest($request, 'rangeStart'));
 
     $saved->setParameter(
       'rangeEnd',
       $this->readDateFromRequest($request, 'rangeEnd'));
 
     $saved->setParameter(
       'upcoming',
       $this->readBoolFromRequest($request, 'upcoming'));
 
     $saved->setParameter(
       'invitedPHIDs',
       $this->readUsersFromRequest($request, 'invited'));
 
     $saved->setParameter(
       'creatorPHIDs',
       $this->readUsersFromRequest($request, 'creators'));
 
     $saved->setParameter(
       'isCancelled',
       $request->getStr('isCancelled'));
 
     $saved->setParameter(
       'display',
       $request->getStr('display'));
 
     return $saved;
   }
 
   public function buildQueryFromSavedQuery(PhabricatorSavedQuery $saved) {
     $query = id(new PhabricatorCalendarEventQuery());
     $viewer = $this->requireViewer();
     $timezone = new DateTimeZone($viewer->getTimezoneIdentifier());
 
     $min_range = $this->getDateFrom($saved)->getEpoch();
     $max_range = $this->getDateTo($saved)->getEpoch();
 
     if ($this->isMonthView($saved) ||
       $this->isDayView($saved)) {
       list($start_year, $start_month, $start_day) =
         $this->getDisplayYearAndMonthAndDay($saved);
 
       $start_day = new DateTime(
         "{$start_year}-{$start_month}-{$start_day}",
         $timezone);
       $next = clone $start_day;
 
       if ($this->isMonthView($saved)) {
         $next->modify('+1 month');
       } else if ($this->isDayView($saved)) {
         $next->modify('+6 day');
       }
 
       $display_start = $start_day->format('U');
       $display_end = $next->format('U');
 
-      // 0 = Sunday is always the start of the week, for now
-      $start_of_week = 0;
-      $end_of_week = 6 - $start_of_week;
+      $preferences = $viewer->loadPreferences();
+      $pref_week_day = PhabricatorUserPreferences::PREFERENCE_WEEK_START_DAY;
+
+      $start_of_week = $preferences->getPreference($pref_week_day, 0);
+      $end_of_week = ($start_of_week + 6) % 7;
 
       $first_of_month = $start_day->format('w');
       $last_of_month = id(clone $next)->modify('-1 day')->format('w');
 
       if (!$min_range || ($min_range < $display_start)) {
         $min_range = $display_start;
 
         if ($this->isMonthView($saved) &&
-          $first_of_month > $start_of_week) {
+          $first_of_month !== $start_of_week) {
+          $interim_day_num = ($first_of_month + 7 - $start_of_week) % 7;
           $min_range = id(clone $start_day)
-            ->modify('-'.$first_of_month.' days')
+            ->modify('-'.$interim_day_num.' days')
             ->format('U');
         }
       }
       if (!$max_range || ($max_range > $display_end)) {
         $max_range = $display_end;
 
         if ($this->isMonthView($saved) &&
-          $last_of_month < $end_of_week) {
+          $last_of_month !== $end_of_week) {
+          $interim_day_num = ($end_of_week + 7 - $last_of_month) % 7;
           $max_range = id(clone $next)
-            ->modify('+'.(6 - $first_of_month).' days')
+            ->modify('+'.$interim_day_num.' days')
             ->format('U');
         }
 
       }
     }
 
     if ($saved->getParameter('upcoming')) {
       if ($min_range) {
         $min_range = max(time(), $min_range);
       } else {
         $min_range = time();
       }
     }
 
     if ($min_range || $max_range) {
       $query->withDateRange($min_range, $max_range);
     }
 
     $invited_phids = $saved->getParameter('invitedPHIDs');
     if ($invited_phids) {
       $query->withInvitedPHIDs($invited_phids);
     }
 
     $creator_phids = $saved->getParameter('creatorPHIDs');
     if ($creator_phids) {
       $query->withCreatorPHIDs($creator_phids);
     }
 
     $is_cancelled = $saved->getParameter('isCancelled');
     switch ($is_cancelled) {
       case 'active':
         $query->withIsCancelled(false);
         break;
       case 'cancelled':
         $query->withIsCancelled(true);
         break;
     }
 
     return $query;
   }
 
   public function buildSearchForm(
     AphrontFormView $form,
     PhabricatorSavedQuery $saved) {
 
     $range_start = $this->getDateFrom($saved);
     $e_start = null;
 
     $range_end = $this->getDateTo($saved);
     $e_end = null;
 
     if (!$range_start->isValid()) {
       $this->addError(pht('Start date is not valid.'));
       $e_start = pht('Invalid');
     }
 
     if (!$range_end->isValid()) {
       $this->addError(pht('End date is not valid.'));
       $e_end = pht('Invalid');
     }
 
     $start_epoch = $range_start->getEpoch();
     $end_epoch = $range_end->getEpoch();
 
     if ($start_epoch && $end_epoch && ($start_epoch > $end_epoch)) {
       $this->addError(pht('End date must be after start date.'));
       $e_start = pht('Invalid');
       $e_end = pht('Invalid');
     }
 
     $upcoming = $saved->getParameter('upcoming');
     $is_cancelled = $saved->getParameter('isCancelled', 'active');
     $display = $saved->getParameter('display', 'month');
 
     $invited_phids = $saved->getParameter('invitedPHIDs', array());
     $creator_phids = $saved->getParameter('creatorPHIDs', array());
     $resolution_types = array(
       'active' => pht('Active Events Only'),
       'cancelled' => pht('Cancelled Events Only'),
       'both' => pht('Both Cancelled and Active Events'),
     );
     $display_options = array(
       'month' => pht('Month View'),
       'day' => pht('Day View (beta)'),
       'list' => pht('List View'),
     );
 
     $form
       ->appendControl(
         id(new AphrontFormTokenizerControl())
           ->setDatasource(new PhabricatorPeopleDatasource())
           ->setName('creators')
           ->setLabel(pht('Created By'))
           ->setValue($creator_phids))
       ->appendControl(
         id(new AphrontFormTokenizerControl())
           ->setDatasource(new PhabricatorPeopleDatasource())
           ->setName('invited')
           ->setLabel(pht('Invited'))
           ->setValue($invited_phids))
       ->appendChild(
         id(new AphrontFormDateControl())
           ->setLabel(pht('Occurs After'))
           ->setUser($this->requireViewer())
           ->setName('rangeStart')
           ->setError($e_start)
           ->setValue($range_start))
       ->appendChild(
         id(new AphrontFormDateControl())
           ->setLabel(pht('Occurs Before'))
           ->setUser($this->requireViewer())
           ->setName('rangeEnd')
           ->setError($e_end)
           ->setValue($range_end))
       ->appendChild(
         id(new AphrontFormCheckboxControl())
           ->addCheckbox(
             'upcoming',
             1,
             pht('Show only upcoming events.'),
             $upcoming))
       ->appendChild(
         id(new AphrontFormSelectControl())
           ->setLabel(pht('Cancelled Events'))
           ->setName('isCancelled')
           ->setValue($is_cancelled)
           ->setOptions($resolution_types))
       ->appendChild(
         id(new AphrontFormSelectControl())
           ->setLabel(pht('Display Options'))
           ->setName('display')
           ->setValue($display)
           ->setOptions($display_options));
   }
 
   protected function getURI($path) {
     return '/calendar/'.$path;
   }
 
   protected function getBuiltinQueryNames() {
     $names = array(
       'month' => pht('Month View'),
       'day' => pht('Day View'),
       'upcoming' => pht('Upcoming Events'),
       'all' => pht('All Events'),
     );
 
     return $names;
   }
 
   public function setCalendarYearAndMonthAndDay($year, $month, $day = null) {
     $this->calendarYear = $year;
     $this->calendarMonth = $month;
     $this->calendarDay = $day;
 
     return $this;
   }
 
   public function buildSavedQueryFromBuiltin($query_key) {
     $query = $this->newSavedQuery();
     $query->setQueryKey($query_key);
 
     switch ($query_key) {
       case 'month':
         return $query->setParameter('display', 'month');
       case 'day':
         return $query->setParameter('display', 'day');
       case 'upcoming':
         return $query->setParameter('upcoming', true);
       case 'all':
         return $query;
     }
 
     return parent::buildSavedQueryFromBuiltin($query_key);
   }
 
   protected function getRequiredHandlePHIDsForResultList(
     array $objects,
     PhabricatorSavedQuery $query) {
     $phids = array();
     foreach ($objects as $event) {
       $phids[$event->getUserPHID()] = 1;
     }
     return array_keys($phids);
   }
 
   protected function renderResultList(
     array $events,
     PhabricatorSavedQuery $query,
     array $handles) {
 
     if ($this->isMonthView($query)) {
       return $this->buildCalendarView($events, $query, $handles);
     } else if ($this->isDayView($query)) {
       return $this->buildCalendarDayView($events, $query, $handles);
     }
 
     assert_instances_of($events, 'PhabricatorCalendarEvent');
     $viewer = $this->requireViewer();
     $list = new PHUIObjectItemListView();
     foreach ($events as $event) {
       $href = '/E'.$event->getID();
       $from = phabricator_datetime($event->getDateFrom(), $viewer);
       $to = phabricator_datetime($event->getDateTo(), $viewer);
       $creator_handle = $handles[$event->getUserPHID()];
 
       $item = id(new PHUIObjectItemView())
         ->setHeader($event->getName())
         ->setHref($href)
         ->addByline(pht('Creator: %s', $creator_handle->renderLink()))
         ->addAttribute(pht('From %s to %s', $from, $to))
         ->addAttribute(id(new PhutilUTF8StringTruncator())
           ->setMaximumGlyphs(64)
           ->truncateString($event->getDescription()));
 
       $list->addItem($item);
     }
 
     return $list;
   }
 
   private function buildCalendarView(
     array $statuses,
     PhabricatorSavedQuery $query,
     array $handles) {
     $viewer = $this->requireViewer();
     $now = time();
 
     list($start_year, $start_month) =
       $this->getDisplayYearAndMonthAndDay($query);
 
     $now_year  = phabricator_format_local_time($now, $viewer, 'Y');
     $now_month = phabricator_format_local_time($now, $viewer, 'm');
     $now_day   = phabricator_format_local_time($now, $viewer, 'j');
 
     if ($start_month == $now_month && $start_year == $now_year) {
       $month_view = new PHUICalendarMonthView(
         $this->getDateFrom($query),
         $this->getDateTo($query),
         $start_month,
         $start_year,
         $now_day);
     } else {
       $month_view = new PHUICalendarMonthView(
         $this->getDateFrom($query),
         $this->getDateTo($query),
         $start_month,
         $start_year);
     }
 
     $month_view->setUser($viewer);
 
     $phids = mpull($statuses, 'getUserPHID');
 
     foreach ($statuses as $status) {
       $viewer_is_invited = $status->getIsUserInvited($viewer->getPHID());
 
       $event = new AphrontCalendarEventView();
       $event->setEpochRange($status->getDateFrom(), $status->getDateTo());
       $event->setIsAllDay($status->getIsAllDay());
 
       $name_text = $handles[$status->getUserPHID()]->getName();
       $status_text = $status->getName();
       $event->setUserPHID($status->getUserPHID());
       $event->setDescription(pht('%s (%s)', $name_text, $status_text));
       $event->setName($status_text);
       $event->setEventID($status->getID());
       $event->setViewerIsInvited($viewer_is_invited);
       $month_view->addEvent($event);
     }
 
     $month_view->setBrowseURI(
       $this->getURI('query/'.$query->getQueryKey().'/'));
 
     return $month_view;
   }
 
   private function buildCalendarDayView(
     array $statuses,
     PhabricatorSavedQuery $query,
     array $handles) {
     $viewer = $this->requireViewer();
     list($start_year, $start_month, $start_day) =
       $this->getDisplayYearAndMonthAndDay($query);
 
     $day_view = new PHUICalendarDayView(
       $this->getDateFrom($query),
       $this->getDateTo($query),
       $start_year,
       $start_month,
       $start_day);
 
     $day_view->setUser($viewer);
 
     $phids = mpull($statuses, 'getUserPHID');
 
     foreach ($statuses as $status) {
       if ($status->getIsCancelled()) {
         continue;
       }
 
       $viewer_is_invited = $status->getIsUserInvited($viewer->getPHID());
 
       $event = new AphrontCalendarEventView();
       $event->setEventID($status->getID());
       $event->setEpochRange($status->getDateFrom(), $status->getDateTo());
       $event->setIsAllDay($status->getIsAllDay());
       $event->setViewerIsInvited($viewer_is_invited);
 
       $event->setName($status->getName());
       $event->setURI('/'.$status->getMonogram());
       $day_view->addEvent($event);
     }
 
     $day_view->setBrowseURI(
       $this->getURI('query/'.$query->getQueryKey().'/'));
 
     return $day_view;
   }
 
   private function getDisplayYearAndMonthAndDay(
     PhabricatorSavedQuery $query) {
     $viewer = $this->requireViewer();
     if ($this->calendarYear && $this->calendarMonth) {
       $start_year = $this->calendarYear;
       $start_month = $this->calendarMonth;
       $start_day = $this->calendarDay ? $this->calendarDay : 1;
     } else {
       $epoch = $this->getDateFrom($query)->getEpoch();
       if (!$epoch) {
         $epoch = $this->getDateTo($query)->getEpoch();
         if (!$epoch) {
           $epoch = time();
         }
       }
       if ($this->isMonthView($query)) {
         $day = 1;
       } else {
         $day = phabricator_format_local_time($epoch, $viewer, 'd');
       }
       $start_year = phabricator_format_local_time($epoch, $viewer, 'Y');
       $start_month = phabricator_format_local_time($epoch, $viewer, 'm');
       $start_day = $day;
     }
     return array($start_year, $start_month, $start_day);
   }
 
   public function getPageSize(PhabricatorSavedQuery $saved) {
     return $saved->getParameter('limit', 1000);
   }
 
   private function getDateFrom(PhabricatorSavedQuery $saved) {
     return $this->getDate($saved, 'rangeStart');
   }
 
   private function getDateTo(PhabricatorSavedQuery $saved) {
     return $this->getDate($saved, 'rangeEnd');
   }
 
   private function getDate(PhabricatorSavedQuery $saved, $key) {
     $viewer = $this->requireViewer();
 
     $wild = $saved->getParameter($key);
     if ($wild) {
       $value = AphrontFormDateControlValue::newFromWild($viewer, $wild);
     } else {
       $value = AphrontFormDateControlValue::newFromEpoch(
         $viewer,
         PhabricatorTime::getTodayMidnightDateTime($viewer)->format('U'));
       $value->setEnabled(false);
     }
 
     $value->setOptional(true);
 
     return $value;
   }
 
   private function isMonthView(PhabricatorSavedQuery $query) {
     if ($this->isDayView($query)) {
       return false;
     }
     if ($query->getParameter('display') == 'month') {
       return true;
     }
   }
 
   private function isDayView(PhabricatorSavedQuery $query) {
     if ($query->getParameter('display') == 'day') {
       return true;
     }
     if ($this->calendarDay) {
       return true;
     }
 
     return false;
   }
 }
diff --git a/src/applications/settings/panel/PhabricatorDateTimeSettingsPanel.php b/src/applications/settings/panel/PhabricatorDateTimeSettingsPanel.php
index 661a1172b7..5fbf825d22 100644
--- a/src/applications/settings/panel/PhabricatorDateTimeSettingsPanel.php
+++ b/src/applications/settings/panel/PhabricatorDateTimeSettingsPanel.php
@@ -1,89 +1,115 @@
 <?php
 
 final class PhabricatorDateTimeSettingsPanel extends PhabricatorSettingsPanel {
 
   public function getPanelKey() {
     return 'datetime';
   }
 
   public function getPanelName() {
     return pht('Date and Time');
   }
 
   public function getPanelGroup() {
     return pht('Account Information');
   }
 
   public function processRequest(AphrontRequest $request) {
     $user = $request->getUser();
     $username = $user->getUsername();
 
     $pref_time = PhabricatorUserPreferences::PREFERENCE_TIME_FORMAT;
+    $pref_week_start = PhabricatorUserPreferences::PREFERENCE_WEEK_START_DAY;
     $preferences = $user->loadPreferences();
 
     $errors = array();
     if ($request->isFormPost()) {
       $new_timezone = $request->getStr('timezone');
       if (in_array($new_timezone, DateTimeZone::listIdentifiers(), true)) {
         $user->setTimezoneIdentifier($new_timezone);
       } else {
         $errors[] = pht('The selected timezone is not a valid timezone.');
       }
 
-      $preferences->setPreference($pref_time, $request->getStr($pref_time));
+      $preferences->setPreference(
+        $pref_time,
+        $request->getStr($pref_time));
+      $preferences->setPreference(
+        $pref_week_start,
+        $request->getStr($pref_week_start));
 
       if (!$errors) {
         $preferences->save();
         $user->save();
         return id(new AphrontRedirectResponse())
           ->setURI($this->getPanelURI('?saved=true'));
       }
     }
 
     $timezone_ids = DateTimeZone::listIdentifiers();
     $timezone_id_map = array_fuse($timezone_ids);
 
     $form = new AphrontFormView();
     $form
       ->setUser($user)
       ->appendChild(
         id(new AphrontFormSelectControl())
           ->setLabel(pht('Timezone'))
           ->setName('timezone')
           ->setOptions($timezone_id_map)
           ->setValue($user->getTimezoneIdentifier()))
       ->appendRemarkupInstructions(
         pht(
           "**Custom Date and Time Formats**\n\n".
           "You can specify custom formats which will be used when ".
           "rendering dates and times of day. Examples:\n\n".
           "| Format  | Example  | Notes |\n".
           "| ------  | -------- | ----- |\n".
           "| `g:i A` | 2:34 PM  | Default 12-hour time. |\n".
           "| `G.i a` | 02.34 pm | Alternate 12-hour time. |\n".
           "| `H:i`   | 14:34    | 24-hour time. |\n".
           "\n\n".
           "You can find a [[%s | full reference in the PHP manual]].",
           'http://www.php.net/manual/en/function.date.php'))
       ->appendChild(
         id(new AphrontFormTextControl())
           ->setLabel(pht('Time-of-Day Format'))
           ->setName($pref_time)
           ->setCaption(
             pht('Format used when rendering a time of day.'))
           ->setValue($preferences->getPreference($pref_time)))
+      ->appendChild(
+        id(new AphrontFormSelectControl())
+          ->setLabel(pht('Week Starts On'))
+          ->setOptions($this->getWeekDays())
+          ->setName($pref_week_start)
+          ->setCaption(
+            pht('Calendar weeks will start with this day.'))
+          ->setValue($preferences->getPreference($pref_week_start, 0)))
       ->appendChild(
         id(new AphrontFormSubmitControl())
           ->setValue(pht('Save Account Settings')));
 
     $form_box = id(new PHUIObjectBoxView())
       ->setHeaderText(pht('Date and Time Settings'))
       ->setFormSaved($request->getStr('saved'))
       ->setFormErrors($errors)
       ->setForm($form);
 
     return array(
       $form_box,
     );
   }
+
+  private function getWeekDays() {
+    return array(
+      pht('Sunday'),
+      pht('Monday'),
+      pht('Tuesday'),
+      pht('Wednesday'),
+      pht('Thursday'),
+      pht('Friday'),
+      pht('Saturday'),
+    );
+  }
 }
diff --git a/src/applications/settings/storage/PhabricatorUserPreferences.php b/src/applications/settings/storage/PhabricatorUserPreferences.php
index 3248dc8b2a..7732df5568 100644
--- a/src/applications/settings/storage/PhabricatorUserPreferences.php
+++ b/src/applications/settings/storage/PhabricatorUserPreferences.php
@@ -1,111 +1,112 @@
 <?php
 
 final class PhabricatorUserPreferences extends PhabricatorUserDAO {
 
   const PREFERENCE_MONOSPACED           = 'monospaced';
   const PREFERENCE_DARK_CONSOLE         = 'dark_console';
   const PREFERENCE_EDITOR               = 'editor';
   const PREFERENCE_MULTIEDIT            = 'multiedit';
   const PREFERENCE_TITLES               = 'titles';
   const PREFERENCE_MONOSPACED_TEXTAREAS = 'monospaced-textareas';
   const PREFERENCE_TIME_FORMAT          = 'time-format';
+  const PREFERENCE_WEEK_START_DAY       = 'week-start-day';
 
   const PREFERENCE_RE_PREFIX            = 're-prefix';
   const PREFERENCE_NO_SELF_MAIL         = 'self-mail';
   const PREFERENCE_NO_MAIL              = 'no-mail';
   const PREFERENCE_MAILTAGS             = 'mailtags';
   const PREFERENCE_VARY_SUBJECT         = 'vary-subject';
   const PREFERENCE_HTML_EMAILS          = 'html-emails';
 
   const PREFERENCE_SEARCHBAR_JUMP       = 'searchbar-jump';
   const PREFERENCE_SEARCH_SHORTCUT      = 'search-shortcut';
   const PREFERENCE_SEARCH_SCOPE = 'search-scope';
 
   const PREFERENCE_DIFFUSION_BLAME      = 'diffusion-blame';
   const PREFERENCE_DIFFUSION_COLOR      = 'diffusion-color';
 
   const PREFERENCE_NAV_COLLAPSED        = 'nav-collapsed';
   const PREFERENCE_NAV_WIDTH            = 'nav-width';
   const PREFERENCE_APP_TILES            = 'app-tiles';
   const PREFERENCE_APP_PINNED           = 'app-pinned';
 
   const PREFERENCE_DIFF_UNIFIED         = 'diff-unified';
   const PREFERENCE_DIFF_FILETREE        = 'diff-filetree';
   const PREFERENCE_DIFF_GHOSTS = 'diff-ghosts';
 
   const PREFERENCE_CONPH_NOTIFICATIONS = 'conph-notifications';
   const PREFERENCE_CONPHERENCE_COLUMN = 'conpherence-column';
 
   // These are in an unusual order for historic reasons.
   const MAILTAG_PREFERENCE_NOTIFY       = 0;
   const MAILTAG_PREFERENCE_EMAIL        = 1;
   const MAILTAG_PREFERENCE_IGNORE       = 2;
 
   protected $userPHID;
   protected $preferences = array();
 
   protected function getConfiguration() {
     return array(
       self::CONFIG_SERIALIZATION => array(
         'preferences' => self::SERIALIZATION_JSON,
       ),
       self::CONFIG_TIMESTAMPS => false,
       self::CONFIG_KEY_SCHEMA => array(
         'userPHID' => array(
           'columns' => array('userPHID'),
           'unique' => true,
         ),
       ),
     ) + parent::getConfiguration();
   }
 
   public function getPreference($key, $default = null) {
     return idx($this->preferences, $key, $default);
   }
 
   public function setPreference($key, $value) {
     $this->preferences[$key] = $value;
     return $this;
   }
 
   public function unsetPreference($key) {
     unset($this->preferences[$key]);
     return $this;
   }
 
   public function getPinnedApplications(array $apps, PhabricatorUser $viewer) {
     $pref_pinned = self::PREFERENCE_APP_PINNED;
     $pinned = $this->getPreference($pref_pinned);
 
     if ($pinned) {
       return $pinned;
     }
 
     $pref_tiles = self::PREFERENCE_APP_TILES;
     $tiles = $this->getPreference($pref_tiles, array());
     $full_tile = 'full';
 
     $large = array();
     foreach ($apps as $app) {
       $show = $app->isPinnedByDefault($viewer);
 
       // TODO: This is legacy stuff, clean it up eventually. This approximately
       // retains the old "tiles" preference.
       if (isset($tiles[get_class($app)])) {
         $show = ($tiles[get_class($app)] == $full_tile);
       }
 
       if ($show) {
         $large[] = get_class($app);
       }
     }
 
     return $large;
   }
 
   public static function filterMonospacedCSSRule($monospaced) {
     // Prevent the user from doing dangerous things.
     return preg_replace('/[^a-z0-9 ,".]+/i', '', $monospaced);
   }
 
 }
diff --git a/src/view/phui/calendar/PHUICalendarMonthView.php b/src/view/phui/calendar/PHUICalendarMonthView.php
index fd2ca4e458..d6bb7d1a32 100644
--- a/src/view/phui/calendar/PHUICalendarMonthView.php
+++ b/src/view/phui/calendar/PHUICalendarMonthView.php
@@ -1,545 +1,549 @@
 <?php
 
 final class PHUICalendarMonthView extends AphrontView {
   private $rangeStart;
   private $rangeEnd;
 
   private $day;
   private $month;
   private $year;
   private $events   = array();
   private $browseURI;
   private $image;
   private $error;
 
   public function setBrowseURI($browse_uri) {
     $this->browseURI = $browse_uri;
     return $this;
   }
   private function getBrowseURI() {
     return $this->browseURI;
   }
 
   public function addEvent(AphrontCalendarEventView $event) {
     $this->events[] = $event;
     return $this;
   }
 
   public function setImage($uri) {
     $this->image = $uri;
     return $this;
   }
 
   public function setInfoView(PHUIInfoView $error) {
     $this->error = $error;
     return $this;
   }
 
   public function __construct(
     $range_start,
     $range_end,
     $month,
     $year,
     $day = null) {
 
     $this->rangeStart = $range_start;
     $this->rangeEnd = $range_end;
 
     $this->day = $day;
     $this->month = $month;
     $this->year = $year;
   }
 
   public function render() {
     if (empty($this->user)) {
       throw new PhutilInvalidStateException('setUser');
     }
 
     $events = msort($this->events, 'getEpochStart');
     $days = $this->getDatesInMonth();
 
     $cell_lists = array();
-    $empty_cell = array(
-        'list' => null,
-        'date' => null,
-        'uri' => null,
-        'count' => 0,
-        'class' => null,
-      );
 
     require_celerity_resource('phui-calendar-month-css');
 
     $first = reset($days);
-    $start_of_week = 0;
-
-    $empty = $first->format('w');
-
-    for ($ii = 0; $ii < $empty; $ii++) {
-      $cell_lists[] = $empty_cell;
-    }
 
     foreach ($days as $day) {
       $day_number = $day->format('j');
 
       $class = 'phui-calendar-month-day';
       $weekday = $day->format('w');
 
       $day->setTime(0, 0, 0);
       $day_start_epoch = $day->format('U');
       $day_end_epoch = id(clone $day)->modify('+1 day')->format('U');
 
       $list_events = array();
       $all_day_events = array();
 
       foreach ($events as $event) {
         if ($event->getEpochStart() >= $day_end_epoch) {
           break;
         }
         if ($event->getEpochStart() < $day_end_epoch &&
             $event->getEpochEnd() > $day_start_epoch) {
           if ($event->getIsAllDay()) {
             $all_day_events[] = $event;
           } else {
             $list_events[] = $event;
           }
         }
       }
 
       $list = new PHUICalendarListView();
       $list->setUser($this->user);
       foreach ($all_day_events as $item) {
         $list->addEvent($item);
       }
       foreach ($list_events as $item) {
         $list->addEvent($item);
       }
 
       $uri = $this->getBrowseURI();
       $uri = $uri.$day->format('Y').'/'.
         $day->format('m').'/'.
         $day->format('d').'/';
 
       $cell_lists[] = array(
         'list' => $list,
         'date' => $day,
         'uri' => $uri,
         'count' => count($all_day_events) + count($list_events),
         'class' => $class,
         );
     }
 
     $rows = array();
     $cell_lists_by_week = array_chunk($cell_lists, 7);
 
     foreach ($cell_lists_by_week as $week_of_cell_lists) {
       $cells = array();
-      while (count($week_of_cell_lists) < 7) {
-        $week_of_cell_lists[] = $empty_cell;
-      }
       foreach ($week_of_cell_lists as $cell_list) {
         $cells[] = $this->getEventListCell($cell_list);
       }
       $rows[] = phutil_tag('tr', array(), $cells);
 
       $cells = array();
       foreach ($week_of_cell_lists as $cell_list) {
         $cells[] = $this->getDayNumberCell($cell_list);
       }
       $rows[] = phutil_tag('tr', array(), $cells);
     }
 
     $header = $this->getDayNamesHeader();
 
     $table = phutil_tag(
       'table',
       array('class' => 'phui-calendar-view'),
       array(
         $header,
         $rows,
       ));
 
     $warnings = $this->getQueryRangeWarning();
 
     $box = id(new PHUIObjectBoxView())
       ->setHeader($this->renderCalendarHeader($first))
       ->appendChild($table)
       ->setFormErrors($warnings);
     if ($this->error) {
       $box->setInfoView($this->error);
 
     }
 
     return $box;
   }
 
   private function getEventListCell($event_list) {
     $list = $event_list['list'];
     $class = $event_list['class'];
     $uri = $event_list['uri'];
     $count = $event_list['count'];
 
     $viewer_is_invited = $list->getIsViewerInvitedOnList();
 
     $event_count_badge = $this->getEventCountBadge($count, $viewer_is_invited);
     $cell_day_secret_link = $this->getHiddenDayLink($uri);
 
     $cell_data_div = phutil_tag(
       'div',
       array(
         'class' => 'phui-calendar-month-cell-div',
       ),
       array(
         $cell_day_secret_link,
         $event_count_badge,
         $list,
       ));
 
     return phutil_tag(
       'td',
       array(
         'class' => 'phui-calendar-month-event-list '.$class,
       ),
       $cell_data_div);
   }
 
   private function getDayNumberCell($event_list) {
     $class = $event_list['class'];
     $date = $event_list['date'];
     $cell_day_secret_link = null;
 
     if ($date) {
       $uri = $event_list['uri'];
       $cell_day_secret_link = $this->getHiddenDayLink($uri);
 
       $cell_day = phutil_tag(
         'a',
         array(
           'class' => 'phui-calendar-date-number',
           'href' => $uri,
         ),
         $date->format('j'));
     } else {
       $cell_day = null;
     }
 
     if ($date && $date->format('j') == $this->day) {
       $today_class = 'phui-calendar-today-slot phui-calendar-today';
     } else {
       $today_class = 'phui-calendar-today-slot';
     }
 
     if ($this->isDateInCurrentWeek($date)) {
       $today_class .= ' phui-calendar-this-week';
     }
 
     $last_week_day = 6;
     if ($date->format('w') == $last_week_day) {
       $today_class .= ' last-weekday';
     }
 
     $today_slot = phutil_tag (
       'div',
       array(
         'class' => $today_class,
       ),
       null);
 
     $cell_div = phutil_tag(
       'div',
       array(
         'class' => 'phui-calendar-month-cell-div',
       ),
       array(
         $cell_day_secret_link,
         $cell_day,
         $today_slot,
       ));
 
     return phutil_tag(
       'td',
       array(
         'class' => 'phui-calendar-date-number-container '.$class,
       ),
       $cell_div);
   }
 
   private function isDateInCurrentWeek($date) {
     list($week_start_date, $week_end_date) = $this->getThisWeekRange();
 
     if ($date->format('U') < $week_end_date->format('U') &&
       $date->format('U') >= $week_start_date->format('U')) {
       return true;
     }
     return false;
   }
 
   private function getEventCountBadge($count, $viewer_is_invited) {
     $class = 'phui-calendar-month-count-badge';
 
     if ($viewer_is_invited) {
       $class = $class.' viewer-invited-day-badge';
     }
 
     $event_count = null;
     if ($count > 0) {
       $event_count = phutil_tag(
         'div',
         array(
           'class' => $class,
         ),
         $count);
     }
 
     return phutil_tag(
       'div',
       array(
         'class' => 'phui-calendar-month-event-count',
       ),
       $event_count);
   }
 
   private function getHiddenDayLink($uri) {
     return phutil_tag(
       'a',
       array(
         'class' => 'phui-calendar-month-secret-link',
         'href' => $uri,
       ),
       null);
   }
 
   private function getDayNamesHeader() {
+    list($week_start, $week_end) = $this->getWeekStartAndEnd();
+
+    $weekday_names = array(
+      $this->getDayHeader(pht('Sun'), pht('Sunday'), true),
+      $this->getDayHeader(pht('Mon'), pht('Monday')),
+      $this->getDayHeader(pht('Tue'), pht('Tuesday')),
+      $this->getDayHeader(pht('Wed'), pht('Wednesday')),
+      $this->getDayHeader(pht('Thu'), pht('Thursday')),
+      $this->getDayHeader(pht('Fri'), pht('Friday')),
+      $this->getDayHeader(pht('Sat'), pht('Saturday'), true),
+    );
+
+    $sorted_weekday_names = array();
+
+    for ($i = $week_start; $i < ($week_start + 7); $i++) {
+      $sorted_weekday_names[] = $weekday_names[$i % 7];
+    }
+
     return phutil_tag(
       'tr',
       array('class' => 'phui-calendar-day-of-week-header'),
-      array(
-        $this->getDayHeader(pht('Sun'), pht('Sunday'), true),
-        $this->getDayHeader(pht('Mon'), pht('Monday')),
-        $this->getDayHeader(pht('Tue'), pht('Tuesday')),
-        $this->getDayHeader(pht('Wed'), pht('Wednesday')),
-        $this->getDayHeader(pht('Thu'), pht('Thursday')),
-        $this->getDayHeader(pht('Fri'), pht('Friday')),
-        $this->getDayHeader(pht('Sat'), pht('Saturday'), true),
-      ));
+      $sorted_weekday_names);
   }
 
   private function getDayHeader($short, $long, $is_weekend = false) {
     $class = null;
     if ($is_weekend) {
       $class = 'weekend-day-header';
     }
     $day = array();
     $day[] = phutil_tag(
       'span',
       array(
         'class' => 'long-weekday-name',
       ),
       $long);
     $day[] = phutil_tag(
       'span',
       array(
         'class' => 'short-weekday-name',
       ),
       $short);
     return phutil_tag(
       'th',
       array(
         'class' => $class,
       ),
       $day);
   }
 
   private function renderCalendarHeader(DateTime $date) {
     $button_bar = null;
 
     // check for a browseURI, which means we need "fancy" prev / next UI
     $uri = $this->getBrowseURI();
     if ($uri) {
       list($prev_year, $prev_month) = $this->getPrevYearAndMonth();
       $prev_uri = $uri.$prev_year.'/'.$prev_month.'/';
 
       list($next_year, $next_month) = $this->getNextYearAndMonth();
       $next_uri = $uri.$next_year.'/'.$next_month.'/';
 
       $button_bar = new PHUIButtonBarView();
 
       $left_icon = id(new PHUIIconView())
           ->setIconFont('fa-chevron-left bluegrey');
       $left = id(new PHUIButtonView())
         ->setTag('a')
         ->setColor(PHUIButtonView::GREY)
         ->setHref($prev_uri)
         ->setTitle(pht('Previous Month'))
         ->setIcon($left_icon);
 
       $right_icon = id(new PHUIIconView())
           ->setIconFont('fa-chevron-right bluegrey');
       $right = id(new PHUIButtonView())
         ->setTag('a')
         ->setColor(PHUIButtonView::GREY)
         ->setHref($next_uri)
         ->setTitle(pht('Next Month'))
         ->setIcon($right_icon);
 
       $button_bar->addButton($left);
       $button_bar->addButton($right);
 
     }
 
     $header = id(new PHUIHeaderView())
       ->setHeader($date->format('F Y'));
 
     if ($button_bar) {
       $header->setButtonBar($button_bar);
     }
 
     if ($this->image) {
       $header->setImage($this->image);
     }
 
     return $header;
   }
 
   private function getQueryRangeWarning() {
     $errors = array();
 
     $range_start_epoch = $this->rangeStart->getEpoch();
     $range_end_epoch = $this->rangeEnd->getEpoch();
 
     $month_start = $this->getDateTime();
     $month_end = id(clone $month_start)->modify('+1 month');
 
     $month_start = $month_start->format('U');
     $month_end = $month_end->format('U') - 1;
 
     if (($range_start_epoch != null &&
         $range_start_epoch < $month_end &&
         $range_start_epoch > $month_start) ||
       ($range_end_epoch != null &&
         $range_end_epoch < $month_end &&
         $range_end_epoch > $month_start)) {
       $errors[] = pht('Part of the month is out of range');
     }
 
     if (($this->rangeEnd->getEpoch() != null &&
         $this->rangeEnd->getEpoch() < $month_start) ||
       ($this->rangeStart->getEpoch() != null &&
         $this->rangeStart->getEpoch() > $month_end)) {
       $errors[] = pht('Month is out of query range');
     }
 
     return $errors;
   }
 
   private function getNextYearAndMonth() {
     $next = $this->getDateTime();
     $next->modify('+1 month');
     return array(
       $next->format('Y'),
       $next->format('m'),
     );
   }
 
   private function getPrevYearAndMonth() {
     $prev = $this->getDateTime();
     $prev->modify('-1 month');
     return array(
       $prev->format('Y'),
       $prev->format('m'),
     );
   }
 
   /**
    * Return a DateTime object representing the first moment in each day in the
    * month, according to the user's locale.
    *
    * @return list List of DateTimes, one for each day.
    */
   private function getDatesInMonth() {
     $user = $this->user;
 
     $timezone = new DateTimeZone($user->getTimezoneIdentifier());
 
     $month = $this->month;
     $year = $this->year;
 
     list($next_year, $next_month) = $this->getNextYearAndMonth();
     $end_date = new DateTime("{$next_year}-{$next_month}-01", $timezone);
 
-    $start_of_week = 0;
-    $end_of_week = 6 - $start_of_week;
+    list($start_of_week, $end_of_week) = $this->getWeekStartAndEnd();
+
     $days_in_month = id(clone $end_date)->modify('-1 day')->format('d');
 
     $first_month_day_date = new DateTime("{$year}-{$month}-01", $timezone);
     $last_month_day_date = id(clone $end_date)->modify('-1 day');
 
     $first_weekday_of_month = $first_month_day_date->format('w');
     $last_weekday_of_month = $last_month_day_date->format('w');
 
     $num_days_display = $days_in_month;
-    if ($start_of_week < $first_weekday_of_month) {
-      $num_days_display += $first_weekday_of_month;
+    if ($start_of_week !== $first_weekday_of_month) {
+      $interim_start_num = ($first_weekday_of_month + 7 - $start_of_week) % 7;
+      $num_days_display += $interim_start_num;
+      $day_date = id(clone $first_month_day_date)
+        ->modify('-'.$interim_start_num.' days');
     }
-    if ($end_of_week > $last_weekday_of_month) {
-      $num_days_display += (6 - $last_weekday_of_month);
-      $end_date->modify('+'.(6 - $last_weekday_of_month).' days');
+    if ($end_of_week !== $last_weekday_of_month) {
+      $interim_end_day_num = ($end_of_week - $last_weekday_of_month + 7) % 7;
+      $num_days_display += $interim_end_day_num;
+      $end_date->modify('+'.$interim_end_day_num.' days');
     }
 
     $days = array();
-    $day_date = id(clone $first_month_day_date)
-      ->modify('-'.$first_weekday_of_month.' days');
 
     for ($day = 1; $day <= $num_days_display; $day++) {
       $day_epoch = $day_date->format('U');
       $end_epoch = $end_date->format('U');
       if ($day_epoch >= $end_epoch) {
         break;
       } else {
         $days[] = clone $day_date;
       }
       $day_date->modify('+1 day');
     }
 
     return $days;
   }
 
   private function getTodayMidnight() {
     $viewer = $this->getUser();
     $today = new DateTime('@'.time());
     $today->setTimeZone($viewer->getTimeZone());
     $today->setTime(0, 0, 0);
 
     return $today;
   }
 
   private function getThisWeekRange() {
-    $week_start = 0;
-    $week_end = 6;
+    list($week_start, $week_end) = $this->getWeekStartAndEnd();
 
     $today = $this->getTodayMidnight();
     $date_weekday = $today->format('w');
 
-    $days_from_week_start = $date_weekday - $week_start;
-    $days_to_week_end = $week_end - $date_weekday + 1;
+    $days_from_week_start = ($date_weekday + 7 - $week_start) % 7;
+    $days_to_week_end = 7 - $days_from_week_start;
 
     $modify = '-'.$days_from_week_start.' days';
     $week_start_date = id(clone $today)->modify($modify);
 
     $modify = '+'.$days_to_week_end.' days';
     $week_end_date = id(clone $today)->modify($modify);
 
     return array($week_start_date, $week_end_date);
   }
 
+  private function getWeekStartAndEnd() {
+    $preferences = $this->user->loadPreferences();
+    $pref_week_start = PhabricatorUserPreferences::PREFERENCE_WEEK_START_DAY;
+
+    $week_start = $preferences->getPreference($pref_week_start, 0);
+    $week_end = ($week_start + 6) % 7;
+
+    return array($week_start, $week_end);
+  }
+
   private function getDateTime() {
     $user = $this->user;
     $timezone = new DateTimeZone($user->getTimezoneIdentifier());
 
     $month = $this->month;
     $year = $this->year;
 
     $date = new DateTime("{$year}-{$month}-01 ", $timezone);
 
     return $date;
   }
 }