diff --git a/src/docs/user/cluster/cluster_partitioning.diviner b/src/docs/user/cluster/cluster_partitioning.diviner
--- a/src/docs/user/cluster/cluster_partitioning.diviner
+++ b/src/docs/user/cluster/cluster_partitioning.diviner
@@ -31,6 +31,13 @@
 should review and understand how replication works before you partition. For
 details, see @{Cluster:Databases}.
 
+Databases also support some advanced configuration options. Briefly:
+
+  - `persistent`: Allows use of persistent connections, reducing pressure on
+    outbound ports.
+
+See "Advanced Configuration", below, for additional discussion.
+
 
 What Partitioning Does
 ======================
@@ -196,6 +203,37 @@
 physical host or different physical hosts.
 
 
+Advanced Configuration
+======================
+
+Separate from partitioning, some advanced configuration is supported. These
+options must be set on database specifications in `cluster.databases`. You can
+configure them without actually building a cluster by defining a cluster with
+only one master.
+
+`persistent` //(bool)// Enables persistent connections. Defaults to off.
+
+With persitent connections enabled, Phabricator will keep a pool of database
+connections open between web requests and reuse them when serving subsequent
+requests.
+
+The primary benefit of using persistent connections is that it will greatly
+reduce pressure on how quickly outbound TCP ports are opened and closed. After
+a TCP port closes, it normally can't be used again for about 60 seconds, so
+rapidly cycling ports can cause resource exuastion. If you're seeing failures
+because requests are unable to bind to an outbound port, enabling this option
+is likely to fix the issue. This option may also slightly increase performance.
+
+The cost of using persistent connections is that you may need to raise the
+MySQL `max_connections` setting: although Phabricator will make far fewer
+connections, the connections it does make will be longer-lived. Raising this
+setting will increase MySQL memory requirements and may run into other limits,
+like `open_files_limit`, which may also need to be raised.
+
+Persistent connections are enabled per-database. If you always want to use
+them, set the flag on each configured database in `cluster.databases`.
+
+
 Next Steps
 ==========
 
diff --git a/src/infrastructure/cluster/PhabricatorClusterDatabasesConfigOptionType.php b/src/infrastructure/cluster/PhabricatorClusterDatabasesConfigOptionType.php
--- a/src/infrastructure/cluster/PhabricatorClusterDatabasesConfigOptionType.php
+++ b/src/infrastructure/cluster/PhabricatorClusterDatabasesConfigOptionType.php
@@ -37,6 +37,7 @@
             'disabled' => 'optional bool',
             'master' => 'optional string',
             'partition' => 'optional list<string>',
+            'persistent' => 'optional bool',
           ));
       } catch (Exception $ex) {
         throw new Exception(
diff --git a/src/infrastructure/cluster/PhabricatorDatabaseRef.php b/src/infrastructure/cluster/PhabricatorDatabaseRef.php
--- a/src/infrastructure/cluster/PhabricatorDatabaseRef.php
+++ b/src/infrastructure/cluster/PhabricatorDatabaseRef.php
@@ -40,6 +40,7 @@
   private $applicationMap = array();
   private $masterRef;
   private $replicaRefs = array();
+  private $usePersistentConnections;
 
   public function setHost($host) {
     $this->host = $host;
@@ -171,6 +172,15 @@
     return $this->isDefaultPartition;
   }
 
+  public function setUsePersistentConnections($use_persistent_connections) {
+    $this->usePersistentConnections = $use_persistent_connections;
+    return $this;
+  }
+
+  public function getUsePersistentConnections() {
+    return $this->usePersistentConnections;
+  }
+
   public function setApplicationMap(array $application_map) {
     $this->applicationMap = $application_map;
     return $this;
@@ -582,7 +592,8 @@
       ->setPort($default_port)
       ->setIsIndividual(true)
       ->setIsMaster(true)
-      ->setIsDefaultPartition(true);
+      ->setIsDefaultPartition(true)
+      ->setUsePersistentConnections(false);
   }
 
   public static function getAllReplicaDatabaseRefs() {
@@ -672,9 +683,31 @@
       'database' => null,
       'retries' => $default_retries,
       'timeout' => $default_timeout,
+      'persistent' => $this->getUsePersistentConnections(),
     );
 
-    return self::newRawConnection($spec);
+    $is_cli = (php_sapi_name() == 'cli');
+
+    $use_persistent = false;
+    if (!empty($spec['persistent']) && !$is_cli) {
+      $use_persistent = true;
+    }
+    unset($spec['persistent']);
+
+    $connection = self::newRawConnection($spec);
+
+    // If configured, use persistent connections. See T11672 for details.
+    if ($use_persistent) {
+      $connection->setPersistent($use_persistent);
+    }
+
+    // Unless this is a script running from the CLI, prevent any query from
+    // running for more than 30 seconds. See T10849 for details.
+    if (!$is_cli) {
+      $connection->setQueryTimeout(30);
+    }
+
+    return $connection;
   }
 
   public static function newRawConnection(array $options) {
diff --git a/src/infrastructure/cluster/PhabricatorDatabaseRefParser.php b/src/infrastructure/cluster/PhabricatorDatabaseRefParser.php
--- a/src/infrastructure/cluster/PhabricatorDatabaseRefParser.php
+++ b/src/infrastructure/cluster/PhabricatorDatabaseRefParser.php
@@ -58,13 +58,16 @@
       $role = $server['role'];
       $is_master = ($role == 'master');
 
+      $use_persistent = (bool)idx($server, 'persistent', false);
+
       $ref = id(new PhabricatorDatabaseRef())
         ->setHost($host)
         ->setPort($port)
         ->setUser($user)
         ->setPass($pass)
         ->setDisabled($disabled)
-        ->setIsMaster($is_master);
+        ->setIsMaster($is_master)
+        ->setUsePersistentConnections($use_persistent);
 
       if ($is_master) {
         $master_count++;
diff --git a/src/infrastructure/storage/lisk/PhabricatorLiskDAO.php b/src/infrastructure/storage/lisk/PhabricatorLiskDAO.php
--- a/src/infrastructure/storage/lisk/PhabricatorLiskDAO.php
+++ b/src/infrastructure/storage/lisk/PhabricatorLiskDAO.php
@@ -73,21 +73,6 @@
       $connection->setReadOnly(true);
     }
 
-    // Unless this is a script running from the CLI:
-    //   - (T10849) Prevent any query from running for more than 30 seconds.
-    //   - (T11672) Use persistent connections.
-    if (php_sapi_name() != 'cli') {
-
-      // TODO: For now, disable this until after T11044: it's better at high
-      // load, but causes us to use slightly more connections at low load and
-      // is pushing users over limits like MySQL "max_connections".
-      $use_persistent = false;
-
-      $connection
-        ->setQueryTimeout(30)
-        ->setPersistent($use_persistent);
-    }
-
     return $connection;
   }