diff --git a/resources/sql/autopatches/20180208.maniphest.01.close.sql b/resources/sql/autopatches/20180208.maniphest.01.close.sql
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20180208.maniphest.01.close.sql
@@ -0,0 +1,5 @@
+ALTER TABLE {$NAMESPACE}_maniphest.maniphest_task
+  ADD closedEpoch INT UNSIGNED;
+
+ALTER TABLE {$NAMESPACE}_maniphest.maniphest_task
+  ADD closerPHID VARBINARY(64);
diff --git a/resources/sql/autopatches/20180208.maniphest.02.populate.php b/resources/sql/autopatches/20180208.maniphest.02.populate.php
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20180208.maniphest.02.populate.php
@@ -0,0 +1,65 @@
+<?php
+
+$table = new ManiphestTask();
+$conn = $table->establishConnection('w');
+$viewer = PhabricatorUser::getOmnipotentUser();
+
+foreach (new LiskMigrationIterator($table) as $task) {
+  if ($task->getClosedEpoch()) {
+    // Task already has a closed date.
+    continue;
+  }
+
+  $status = $task->getStatus();
+  if (!ManiphestTaskStatus::isClosedStatus($status)) {
+    // Task isn't closed.
+    continue;
+  }
+
+  // Look through the transactions from newest to oldest until we find one
+  // where the task was closed. A merge also counts as a close, even though
+  // it doesn't currently produce a separate transaction.
+
+  $type_merge = ManiphestTaskStatusTransaction::TRANSACTIONTYPE;
+  $type_status = ManiphestTaskMergedIntoTransaction::TRANSACTIONTYPE;
+
+  $xactions = id(new ManiphestTransactionQuery())
+    ->setViewer($viewer)
+    ->withObjectPHIDs(array($task->getPHID()))
+    ->withTransactionTypes(
+      array(
+        $type_merge,
+        $type_status,
+      ))
+    ->execute();
+  foreach ($xactions as $xaction) {
+    $old = $xaction->getOldValue();
+    $new = $xaction->getNewValue();
+
+    $type = $xaction->getTransactionType();
+
+    // If this is a status change, but is not a close, don't use it.
+    // (We always use merges, even though it's possible to merge a task which
+    // was previously closed: we can't tell when this happens very easily.)
+    if ($type === $type_status) {
+      if (!ManiphestTaskStatus::isClosedStatus($new)) {
+        continue;
+      }
+
+      if ($old && ManiphestTaskStatus::isClosedStatus($old)) {
+        continue;
+      }
+    }
+
+    queryfx(
+      $conn,
+      'UPDATE %T SET closedEpoch = %d, closerPHID = %ns
+        WHERE id = %d',
+      $table->getTableName(),
+      $xaction->getDateCreated(),
+      $xaction->getAuthorPHID(),
+      $task->getID());
+
+    break;
+  }
+}
diff --git a/src/applications/maniphest/storage/ManiphestTask.php b/src/applications/maniphest/storage/ManiphestTask.php
--- a/src/applications/maniphest/storage/ManiphestTask.php
+++ b/src/applications/maniphest/storage/ManiphestTask.php
@@ -44,6 +44,9 @@
   protected $points;
   protected $subtype;
 
+  protected $closedEpoch;
+  protected $closerPHID;
+
   private $subscriberPHIDs = self::ATTACHABLE;
   private $groupByProjectPHID = self::ATTACHABLE;
   private $customFields = self::ATTACHABLE;
@@ -90,6 +93,8 @@
         'points' => 'double?',
         'bridgedObjectPHID' => 'phid?',
         'subtype' => 'text64',
+        'closedEpoch' => 'epoch?',
+        'closerPHID' => 'phid?',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'key_phid' => null,
@@ -131,6 +136,12 @@
         'key_subtype' => array(
           'columns' => array('subtype'),
         ),
+        'key_closed' => array(
+          'columns' => array('closedEpoch'),
+        ),
+        'key_closer' => array(
+          'columns' => array('closerPHID', 'closedEpoch'),
+        ),
       ),
     ) + parent::getConfiguration();
   }
diff --git a/src/applications/maniphest/xaction/ManiphestTaskMergedIntoTransaction.php b/src/applications/maniphest/xaction/ManiphestTaskMergedIntoTransaction.php
--- a/src/applications/maniphest/xaction/ManiphestTaskMergedIntoTransaction.php
+++ b/src/applications/maniphest/xaction/ManiphestTaskMergedIntoTransaction.php
@@ -10,7 +10,7 @@
   }
 
   public function applyInternalEffects($object, $value) {
-    $object->setStatus(ManiphestTaskStatus::getDuplicateStatus());
+    $this->updateStatus($object, ManiphestTaskStatus::getDuplicateStatus());
   }
 
   public function getActionName() {
diff --git a/src/applications/maniphest/xaction/ManiphestTaskStatusTransaction.php b/src/applications/maniphest/xaction/ManiphestTaskStatusTransaction.php
--- a/src/applications/maniphest/xaction/ManiphestTaskStatusTransaction.php
+++ b/src/applications/maniphest/xaction/ManiphestTaskStatusTransaction.php
@@ -10,7 +10,7 @@
   }
 
   public function applyInternalEffects($object, $value) {
-    $object->setStatus($value);
+    $this->updateStatus($object, $value);
   }
 
   public function shouldHide() {
diff --git a/src/applications/maniphest/xaction/ManiphestTaskTransactionType.php b/src/applications/maniphest/xaction/ManiphestTaskTransactionType.php
--- a/src/applications/maniphest/xaction/ManiphestTaskTransactionType.php
+++ b/src/applications/maniphest/xaction/ManiphestTaskTransactionType.php
@@ -3,4 +3,27 @@
 abstract class ManiphestTaskTransactionType
   extends PhabricatorModularTransactionType {
 
+  protected function updateStatus($object, $new_value) {
+    $old_value = $object->getStatus();
+    $object->setStatus($new_value);
+
+    // If this status change closes or opens the task, update the closed
+    // date and actor PHID.
+    $old_closed = ManiphestTaskStatus::isClosedStatus($old_value);
+    $new_closed = ManiphestTaskStatus::isClosedStatus($new_value);
+
+    $is_close = ($new_closed && !$old_closed);
+    $is_open = (!$new_closed && $old_closed);
+
+    if ($is_close) {
+      $object
+        ->setClosedEpoch(PhabricatorTime::getNow())
+        ->setCloserPHID($this->getActingAsPHID());
+    } else if ($is_open) {
+      $object
+        ->setClosedEpoch(null)
+        ->setCloserPHID(null);
+    }
+  }
+
 }