diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 828ec80ad2..8ee103557f 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -531,6 +531,7 @@ phutil_register_library_map(array(
     'PhabricatorCalendarController' => 'applications/calendar/controller/base',
     'PhabricatorCalendarDAO' => 'applications/calendar/storage/base',
     'PhabricatorCalendarHoliday' => 'applications/calendar/storage/holiday',
+    'PhabricatorCalendarHolidayTestCase' => 'applications/calendar/storage/holiday/__tests__',
     'PhabricatorChangesetResponse' => 'infrastructure/diff/response',
     'PhabricatorChatLogChannelListController' => 'applications/chatlog/controller/channellist',
     'PhabricatorChatLogChannelLogController' => 'applications/chatlog/controller/channellog',
@@ -1465,6 +1466,7 @@ phutil_register_library_map(array(
     'PhabricatorCalendarController' => 'PhabricatorController',
     'PhabricatorCalendarDAO' => 'PhabricatorLiskDAO',
     'PhabricatorCalendarHoliday' => 'PhabricatorCalendarDAO',
+    'PhabricatorCalendarHolidayTestCase' => 'PhabricatorTestCase',
     'PhabricatorChangesetResponse' => 'AphrontProxyResponse',
     'PhabricatorChatLogChannelListController' => 'PhabricatorChatLogController',
     'PhabricatorChatLogChannelLogController' => 'PhabricatorChatLogController',
diff --git a/src/applications/calendar/storage/holiday/PhabricatorCalendarHoliday.php b/src/applications/calendar/storage/holiday/PhabricatorCalendarHoliday.php
index 7d0d8d671e..242fff57f9 100644
--- a/src/applications/calendar/storage/holiday/PhabricatorCalendarHoliday.php
+++ b/src/applications/calendar/storage/holiday/PhabricatorCalendarHoliday.php
@@ -27,4 +27,22 @@ final class PhabricatorCalendarHoliday extends PhabricatorCalendarDAO {
     ) + parent::getConfiguration();
   }
 
+  public static function getNthBusinessDay($epoch, $n) {
+    // Sadly, there are not many holidays. So we can load all of them.
+    $holidays = id(new PhabricatorCalendarHoliday())->loadAll();
+    $holidays = mpull($holidays, null, 'getDay');
+    $interval = ($n > 0 ? 1 : -1) * 24 * 60 * 60;
+
+    $return = $epoch;
+    for ($i = abs($n); $i > 0; ) {
+      $return += $interval;
+      $weekday = date('w', $return);
+      if ($weekday != 0 && $weekday != 6 && // Sunday and Saturday
+          !isset($holidays[date('Y-m-d', $return)])) {
+        $i--;
+      }
+    }
+    return $return;
+  }
+
 }
diff --git a/src/applications/calendar/storage/holiday/__init__.php b/src/applications/calendar/storage/holiday/__init__.php
index c5c4a005c2..f761714e78 100644
--- a/src/applications/calendar/storage/holiday/__init__.php
+++ b/src/applications/calendar/storage/holiday/__init__.php
@@ -8,5 +8,7 @@
 
 phutil_require_module('phabricator', 'applications/calendar/storage/base');
 
+phutil_require_module('phutil', 'utils');
+
 
 phutil_require_source('PhabricatorCalendarHoliday.php');
diff --git a/src/applications/calendar/storage/holiday/__tests__/PhabricatorCalendarHolidayTestCase.php b/src/applications/calendar/storage/holiday/__tests__/PhabricatorCalendarHolidayTestCase.php
new file mode 100644
index 0000000000..be0a51b71a
--- /dev/null
+++ b/src/applications/calendar/storage/holiday/__tests__/PhabricatorCalendarHolidayTestCase.php
@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * Copyright 2012 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorCalendarHolidayTestCase extends PhabricatorTestCase {
+
+  protected function getPhabricatorTestCaseConfiguration() {
+    return array(
+      self::PHABRICATOR_TESTCONFIG_BUILD_STORAGE_FIXTURES => true,
+    );
+  }
+
+  protected function willRunTests() {
+    parent::willRunTests();
+    id(new PhabricatorCalendarHoliday())
+      ->setDay('2012-01-02')
+      ->setName('International Testing Day')
+      ->save();
+  }
+
+  public function testNthBusinessDay() {
+    $map = array(
+      array('2011-12-30', 1, '2012-01-03'),
+      array('2012-01-01', 1, '2012-01-03'),
+      array('2012-01-01', 0, '2012-01-01'),
+      array('2012-01-01', -1, '2011-12-30'),
+      array('2012-01-04', -1, '2012-01-03'),
+    );
+    foreach ($map as $val) {
+      list($date, $n, $expect) = $val;
+      $actual = PhabricatorCalendarHoliday::getNthBusinessDay(
+        strtotime($date),
+        $n);
+      $this->assertEqual(
+        $expect,
+        date('Y-m-d', $actual),
+        "{$n} business days since '{$date}'");
+    }
+  }
+
+}
diff --git a/src/applications/calendar/storage/holiday/__tests__/__init__.php b/src/applications/calendar/storage/holiday/__tests__/__init__.php
new file mode 100644
index 0000000000..aa8a9d30b4
--- /dev/null
+++ b/src/applications/calendar/storage/holiday/__tests__/__init__.php
@@ -0,0 +1,15 @@
+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('phabricator', 'applications/calendar/storage/holiday');
+phutil_require_module('phabricator', 'infrastructure/testing/testcase');
+
+phutil_require_module('phutil', 'utils');
+
+
+phutil_require_source('PhabricatorCalendarHolidayTestCase.php');