diff --git a/src/daemon/PhutilDaemonHandle.php b/src/daemon/PhutilDaemonHandle.php
index 988005d..d11973a 100644
--- a/src/daemon/PhutilDaemonHandle.php
+++ b/src/daemon/PhutilDaemonHandle.php
@@ -1,371 +1,379 @@
 <?php
 
 final class PhutilDaemonHandle {
 
   const EVENT_DID_LAUNCH    = 'daemon.didLaunch';
   const EVENT_DID_LOG       = 'daemon.didLogMessage';
   const EVENT_DID_HEARTBEAT = 'daemon.didHeartbeat';
   const EVENT_WILL_GRACEFUL = 'daemon.willGraceful';
   const EVENT_WILL_EXIT     = 'daemon.willExit';
 
   private $overseer;
   private $daemonClass;
   private $argv;
   private $pid;
   private $daemonID;
   private $deadline;
   private $heartbeat;
   private $stdoutBuffer;
   private $restartAt;
   private $silent;
   private $shouldShutdown;
   private $future;
   private $traceMemory;
 
   public function __construct(
     PhutilDaemonOverseer $overseer,
     $daemon_class,
     array $argv,
     array $config) {
 
     $this->overseer = $overseer;
     $this->daemonClass = $daemon_class;
     $this->argv = $argv;
     $this->config = $config;
     $this->restartAt = time();
 
     $this->daemonID = $this->generateDaemonID();
     $this->dispatchEvent(
       self::EVENT_DID_LAUNCH,
       array(
         'argv' => $this->argv,
         'explicitArgv' => idx($this->config, 'argv'),
       ));
   }
 
   public function isRunning() {
     return (bool)$this->future;
   }
 
   public function getFuture() {
     return $this->future;
   }
 
   public function setSilent($silent) {
     $this->silent = $silent;
     return $this;
   }
 
   public function getSilent() {
     return $this->silent;
   }
 
   public function setTraceMemory($trace_memory) {
     $this->traceMemory = $trace_memory;
     return $this;
   }
 
   public function getTraceMemory() {
     return $this->traceMemory;
   }
 
   public function update() {
     $this->updateMemory();
 
     if (!$this->isRunning()) {
       if (!$this->restartAt || (time() < $this->restartAt)) {
         return;
       }
       if ($this->shouldShutdown) {
         return;
       }
       $this->startDaemonProcess();
     }
 
     $future = $this->future;
 
     $result = null;
     if ($future->isReady()) {
       $result = $future->resolve();
     }
 
     list($stdout, $stderr) = $future->read();
     $future->discardBuffers();
 
     if (strlen($stdout)) {
       $this->didReadStdout($stdout);
     }
 
     $stderr = trim($stderr);
     if (strlen($stderr)) {
       $this->logMessage('STDE', $stderr);
     }
 
     if ($result !== null) {
       list($err) = $result;
       if ($err) {
         $this->logMessage('FAIL', pht('Process exited with error %s', $err));
       } else {
         $this->logMessage('DONE', pht('Process exited normally.'));
       }
 
       $this->future = null;
 
       if ($this->shouldShutdown) {
         $this->restartAt = null;
         $this->dispatchEvent(self::EVENT_WILL_EXIT);
       } else {
         $this->scheduleRestart();
       }
     }
 
     $this->updateHeartbeatEvent();
     $this->updateHangDetection();
   }
 
   private function updateHeartbeatEvent() {
     if ($this->heartbeat > time()) {
       return;
     }
 
     $this->heartbeat = time() + $this->getHeartbeatEventFrequency();
     $this->dispatchEvent(self::EVENT_DID_HEARTBEAT);
   }
 
   private function updateHangDetection() {
     if (!$this->isRunning()) {
       return;
     }
 
     if (time() > $this->deadline) {
       $this->logMessage('HANG', pht('Hang detected. Restarting process.'));
       $this->annihilateProcessGroup();
       $this->scheduleRestart();
     }
   }
 
   private function scheduleRestart() {
     $this->logMessage('WAIT', pht('Waiting to restart process.'));
     $this->restartAt = time() + self::getWaitBeforeRestart();
   }
 
   /**
    * Generate a unique ID for this daemon.
    *
    * @return string A unique daemon ID.
    */
   private function generateDaemonID() {
     return substr(getmypid().':'.Filesystem::readRandomCharacters(12), 0, 12);
   }
 
+  public function getDaemonID() {
+    return $this->daemonID;
+  }
+
+  public function getPID() {
+    return $this->pid;
+  }
+
   private function getCaptureBufferSize() {
     return 65535;
   }
 
   private function getRequiredHeartbeatFrequency() {
     return 86400;
   }
 
   public static function getWaitBeforeRestart() {
     return 5;
   }
 
   public static function getHeartbeatEventFrequency() {
     return 120;
   }
 
   private function getKillDelay() {
     return 3;
   }
 
   private function getDaemonCWD() {
     $root = dirname(phutil_get_library_root('phutil'));
     return $root.'/scripts/daemon/exec/';
   }
 
   private function newExecFuture() {
     $class = $this->daemonClass;
     $argv = $this->argv;
     $buffer_size = $this->getCaptureBufferSize();
 
     // NOTE: PHP implements proc_open() by running 'sh -c'. On most systems this
     // is bash, but on Ubuntu it's dash. When you proc_open() using bash, you
     // get one new process (the command you ran). When you proc_open() using
     // dash, you get two new processes: the command you ran and a parent
     // "dash -c" (or "sh -c") process. This means that the child process's PID
     // is actually the 'dash' PID, not the command's PID. To avoid this, use
     // 'exec' to replace the shell process with the real process; without this,
     // the child will call posix_getppid(), be given the pid of the 'sh -c'
     // process, and send it SIGUSR1 to keepalive which will terminate it
     // immediately. We also won't be able to do process group management because
     // the shell process won't properly posix_setsid() so the pgid of the child
     // won't be meaningful.
 
     return id(new ExecFuture('exec ./exec_daemon.php %s %Ls', $class, $argv))
       ->setCWD($this->getDaemonCWD())
       ->setStdoutSizeLimit($buffer_size)
       ->setStderrSizeLimit($buffer_size)
       ->write(json_encode($this->config));
   }
 
   /**
    * Dispatch an event to event listeners.
    *
    * @param  string Event type.
    * @param  dict   Event parameters.
    * @return void
    */
   private function dispatchEvent($type, array $params = array()) {
     $data = array(
       'id' => $this->daemonID,
       'daemonClass' => $this->daemonClass,
       'childPID' => $this->pid,
     ) + $params;
 
     $event = new PhutilEvent($type, $data);
 
     try {
       PhutilEventEngine::dispatchEvent($event);
     } catch (Exception $ex) {
       phlog($ex);
     }
   }
 
   private function annihilateProcessGroup() {
     $pid = $this->pid;
     $pgid = posix_getpgid($pid);
     if ($pid && $pgid) {
 
       // NOTE: On Ubuntu, 'kill' does not recognize the use of "--" to
       // explicitly delineate PID/PGIDs from signals. We don't actually need it,
       // so use the implicit "kill -TERM -pgid" form instead of the explicit
       // "kill -TERM -- -pgid" form.
       exec("kill -TERM -{$pgid}");
       sleep($this->getKillDelay());
 
       // On OSX, we'll get a permission error on stderr if the SIGTERM was
       // successful in ending the life of the process group, presumably because
       // all that's left is the daemon itself as a zombie waiting for us to
       // reap it. However, we still need to issue this command for process
       // groups that resist SIGTERM. Rather than trying to figure out if the
       // process group is still around or not, just SIGKILL unconditionally and
       // ignore any error which may be raised.
       exec("kill -KILL -{$pgid} 2>/dev/null");
       $this->pid = null;
     }
   }
 
 
   private function gracefulProcessGroup() {
     $pid = $this->pid;
     $pgid = posix_getpgid($pid);
     if ($pid && $pgid) {
       exec("kill -INT -{$pgid}");
     }
   }
 
   private function updateMemory() {
     if ($this->traceMemory) {
       $memuse = number_format(memory_get_usage() / 1024, 1);
       $this->logMessage('RAMS', 'Overseer Memory Usage: '.$memuse.' KB');
     }
   }
 
   private function startDaemonProcess() {
     $this->logMessage('INIT', pht('Starting process.'));
 
     $this->deadline = time() + $this->getRequiredHeartbeatFrequency();
     $this->heartbeat = time() + self::getHeartbeatEventFrequency();
     $this->stdoutBuffer = '';
 
     $this->future = $this->newExecFuture();
     $this->future->start();
 
     $this->pid = $this->future->getPID();
   }
 
   private function didReadStdout($data) {
     $this->stdoutBuffer .= $data;
     while (true) {
       $pos = strpos($this->stdoutBuffer, "\n");
       if ($pos === false) {
         break;
       }
       $message = substr($this->stdoutBuffer, 0, $pos);
       $this->stdoutBuffer = substr($this->stdoutBuffer, $pos + 1);
 
       $structure = @json_decode($message, true);
       if (!is_array($structure)) {
         $structure = array();
       }
 
       switch (idx($structure, 0)) {
         case PhutilDaemon::MESSAGETYPE_STDOUT:
           $this->logMessage('STDO', idx($structure, 1));
           break;
         case PhutilDaemon::MESSAGETYPE_HEARTBEAT:
           $this->deadline = time() + $this->getRequiredHeartbeatFrequency();
           break;
         default:
           // If we can't parse this or it isn't a message we understand, just
           // emit the raw message.
           $this->logMessage('STDO', pht('<Malformed> %s', $message));
           break;
       }
     }
   }
 
   public function didReceiveNotifySignal($signo) {
     $pid = $this->pid;
     if ($pid) {
       posix_kill($pid, $signo);
     }
   }
 
   public function didReceiveGracefulSignal($signo) {
     $this->shouldShutdown = true;
 
     $signame = phutil_get_signal_name($signo);
     if ($signame) {
       $sigmsg = pht(
         'Graceful shutdown in response to signal %d (%s).',
         $signo,
         $signame);
     } else {
       $sigmsg = pht(
         'Graceful shutdown in response to signal %d.',
         $signo);
     }
 
     $this->logMessage('DONE', $sigmsg, $signo);
     $this->gracefulProcessGroup();
   }
 
   public function didReceiveTerminalSignal($signo) {
     $signame = phutil_get_signal_name($signo);
     if ($signame) {
       $sigmsg = "Shutting down in response to signal {$signo} ({$signame}).";
     } else {
       $sigmsg = "Shutting down in response to signal {$signo}.";
     }
 
     $this->logMessage('EXIT', $sigmsg, $signo);
     $this->annihilateProcessGroup();
     $this->dispatchEvent(self::EVENT_WILL_EXIT);
   }
 
   private function logMessage($type, $message, $context = null) {
     if (!$this->getSilent()) {
       echo date('Y-m-d g:i:s A').' ['.$type.'] '.$message."\n";
     }
 
     $this->dispatchEvent(
       self::EVENT_DID_LOG,
       array(
         'type' => $type,
         'message' => $message,
         'context' => $context,
       ));
   }
 
 }
diff --git a/src/daemon/PhutilDaemonOverseer.php b/src/daemon/PhutilDaemonOverseer.php
index 27a28f4..5915265 100644
--- a/src/daemon/PhutilDaemonOverseer.php
+++ b/src/daemon/PhutilDaemonOverseer.php
@@ -1,321 +1,339 @@
 <?php
 
 /**
  * Oversees a daemon and restarts it if it fails.
  */
 final class PhutilDaemonOverseer {
 
   private $argv;
   private $moreArgs;
   private $inAbruptShutdown;
   private $inGracefulShutdown;
   private static $instance;
 
-  private $daemon;
+  private $config;
   private $daemons = array();
   private $traceMode;
   private $traceMemory;
   private $daemonize;
-  private $phddir;
+  private $piddir;
   private $log;
   private $libraries = array();
   private $verbose;
   private $err = 0;
+  private $lastPidfile;
+  private $startEpoch;
 
   public function __construct(array $argv) {
     PhutilServiceProfiler::getInstance()->enableDiscardMode();
 
-    $original_argv = $argv;
     $args = new PhutilArgumentParser($argv);
     $args->setTagline('daemon overseer');
     $args->setSynopsis(<<<EOHELP
 **launch_daemon.php** [__options__] __daemon__
     Launch and oversee an instance of __daemon__.
 EOHELP
       );
     $args->parseStandardArguments();
-    $args->parsePartial(
+    $args->parse(
       array(
         array(
           'name' => 'trace-memory',
           'help' => 'Enable debug memory tracing.',
         ),
-        array(
-          'name'  => 'log',
-          'param' => 'file',
-          'help'  => 'Send output to __file__.',
-        ),
-        array(
-          'name'  => 'daemonize',
-          'help'  => 'Run in the background.',
-        ),
-        array(
-          'name'  => 'phd',
-          'param' => 'dir',
-          'help'  => 'Write PID information to __dir__.',
-        ),
         array(
           'name'  => 'verbose',
           'help'  => 'Enable verbose activity logging.',
         ),
         array(
           'name' => 'label',
           'short' => 'l',
           'param' => 'label',
           'help' => pht(
             'Optional process label. Makes "ps" nicer, no behavioral effects.'),
         ),
-        array(
-          'name' => 'load-phutil-library',
-          'param' => 'library',
-          'repeat' => true,
-          'help' => 'Load __library__.',
-        ),
       ));
     $argv = array();
 
-    $more = $args->getUnconsumedArgumentVector();
-
-    $this->daemon = array_shift($more);
-    if (!$this->daemon) {
-      $args->printHelpAndExit();
-    }
-
     if ($args->getArg('trace')) {
       $this->traceMode = true;
       $argv[] = '--trace';
     }
 
     if ($args->getArg('trace-memory')) {
       $this->traceMode = true;
       $this->traceMemory = true;
       $argv[] = '--trace-memory';
     }
-
-    if ($args->getArg('load-phutil-library')) {
-      foreach ($args->getArg('load-phutil-library') as $library) {
-        $this->libraries[] = $library;
-      }
-    }
-
-    $log = $args->getArg('log');
-    if ($log) {
-      $this->log = $log;
-    }
-
     $verbose = $args->getArg('verbose');
     if ($verbose) {
       $this->verbose = true;
       $argv[] = '--verbose';
     }
 
     $label = $args->getArg('label');
     if ($label) {
       $argv[] = '-l';
       $argv[] = $label;
     }
 
-    $this->daemonize = $args->getArg('daemonize');
-    $this->phddir = $args->getArg('phd');
     $this->argv = $argv;
-    $this->moreArgs = coalesce($more, array());
+
+    if (function_exists('posix_isatty') && posix_isatty(STDIN)) {
+      fprintf(STDERR, pht('Reading daemon configuration from stdin...')."\n");
+    }
+    $config = @file_get_contents('php://stdin');
+    $config = id(new PhutilJSONParser())->parse($config);
+
+    $this->libraries = idx($config, 'load');
+    $this->log = idx($config, 'log');
+    $this->daemonize = idx($config, 'daemonize');
+    $this->piddir = idx($config, 'piddir');
+
+    $this->config = $config;
 
     if (self::$instance) {
       throw new Exception(
         'You may not instantiate more than one Overseer per process.');
     }
 
     self::$instance = $this;
 
+    $this->startEpoch = time();
+
     // Check this before we daemonize, since if it's an issue the child will
     // exit immediately.
-    if ($this->phddir) {
-      $dir = $this->phddir;
+    if ($this->piddir) {
+      $dir = $this->piddir;
       try {
         Filesystem::assertWritable($dir);
       } catch (Exception $ex) {
         throw new Exception(
           "Specified daemon PID directory ('{$dir}') does not exist or is ".
           "not writable by the daemon user!");
       }
     }
 
-    if ($log) {
+    if (!idx($config, 'daemons')) {
+      throw new PhutilArgumentUsageException(
+        pht('You must specify at least one daemon to start!'));
+    }
+
+    if ($this->log) {
       // NOTE: Now that we're committed to daemonizing, redirect the error
       // log if we have a `--log` parameter. Do this at the last moment
       // so as many setup issues as possible are surfaced.
-      ini_set('error_log', $log);
+      ini_set('error_log', $this->log);
     }
 
-    error_log("Bringing daemon '{$this->daemon}' online...");
-
     if ($this->daemonize) {
-
       // We need to get rid of these or the daemon will hang when we TERM it
       // waiting for something to read the buffers. TODO: Learn how unix works.
       fclose(STDOUT);
       fclose(STDERR);
       ob_start();
 
       $pid = pcntl_fork();
       if ($pid === -1) {
         throw new Exception('Unable to fork!');
       } else if ($pid) {
         exit(0);
       }
     }
 
-    if ($this->phddir) {
-      $desc = array(
-        'name'            => $this->daemon,
-        'argv'            => $this->moreArgs,
-        'pid'             => getmypid(),
-        'start'           => time(),
-      );
-      Filesystem::writeFile(
-        $this->phddir.'/daemon.'.getmypid(),
-        json_encode($desc));
-    }
-
     declare(ticks = 1);
     pcntl_signal(SIGUSR2, array($this, 'didReceiveNotifySignal'));
 
     pcntl_signal(SIGINT,  array($this, 'didReceiveGracefulSignal'));
     pcntl_signal(SIGTERM, array($this, 'didReceiveTerminalSignal'));
   }
 
+  public function addLibrary($library) {
+    $this->libraries[] = $library;
+    return $this;
+  }
+
   public function run() {
-    $daemon = new PhutilDaemonHandle(
-      $this,
-      $this->daemon,
-      $this->argv,
-      array(
-        'log' => $this->log,
-        'argv' => $this->moreArgs,
-        'load' => $this->libraries,
-      ));
+    $this->daemons = array();
+
+    foreach ($this->config['daemons'] as $config) {
+      $daemon = new PhutilDaemonHandle(
+        $this,
+        $config['class'],
+        $this->argv,
+        array(
+          'log' => $this->log,
+          'argv' => $config['argv'],
+          'load' => $this->libraries,
+        ));
+
+      $daemon->setSilent((!$this->traceMode && !$this->verbose));
+      $daemon->setTraceMemory($this->traceMemory);
 
-    $daemon->setSilent((!$this->traceMode && !$this->verbose));
-    $daemon->setTraceMemory($this->traceMemory);
+      $this->daemons[] = array(
+        'config' => $config,
+        'handle' => $daemon,
+      );
+    }
 
-    $this->daemons = array($daemon);
     while (true) {
       $futures = array();
-      foreach ($this->daemons as $daemon) {
+      foreach ($this->getDaemonHandles() as $daemon) {
         $daemon->update();
         if ($daemon->isRunning()) {
           $futures[] = $daemon->getFuture();
         }
       }
 
+      $this->updatePidfile();
+
       if ($futures) {
         $iter = id(new FutureIterator($futures))
           ->setUpdateInterval(1);
         foreach ($iter as $future) {
           break;
         }
       } else {
         if ($this->inGracefulShutdown) {
           break;
         }
         sleep(1);
       }
     }
 
     exit($this->err);
   }
 
   public function didReceiveNotifySignal($signo) {
-    foreach ($this->daemons as $daemon) {
+    foreach ($this->getDaemonHandles() as $daemon) {
       $daemon->didReceiveNotifySignal($signo);
     }
   }
 
   public function didReceiveGracefulSignal($signo) {
     // If we receive SIGINT more than once, interpret it like SIGTERM.
     if ($this->inGracefulShutdown) {
       return $this->didReceiveTerminalSignal($signo);
     }
     $this->inGracefulShutdown = true;
 
-    foreach ($this->daemons as $daemon) {
+    foreach ($this->getDaemonHandles() as $daemon) {
       $daemon->didReceiveGracefulSignal($signo);
     }
   }
 
   public function didReceiveTerminalSignal($signo) {
     $this->err = 128 + $signo;
     if ($this->inAbruptShutdown) {
       exit($this->err);
     }
     $this->inAbruptShutdown = true;
 
-    foreach ($this->daemons as $daemon) {
+    foreach ($this->getDaemonHandles() as $daemon) {
       $daemon->didReceiveTerminalSignal($signo);
     }
   }
 
+  private function getDaemonHandles() {
+    return ipull($this->daemons, 'handle');
+  }
 
   /**
    * Identify running daemons by examining the process table. This isn't
    * completely reliable, but can be used as a fallback if the pid files fail
    * or we end up with stray daemons by other means.
    *
    * Example output (array keys are process IDs):
    *
    *   array(
    *     12345 => array(
    *       'type' => 'overseer',
    *       'command' => 'php launch_daemon.php --daemonize ...',
    *       'pid' => 12345,
    *     ),
    *     12346 => array(
    *       'type' => 'daemon',
    *       'command' => 'php exec_daemon.php ...',
    *       'pid' => 12346,
    *     ),
    *  );
    *
    * @return dict   Map of PIDs to process information, identifying running
    *                daemon processes.
    */
   public static function findRunningDaemons() {
     $results = array();
 
     list($err, $processes) = exec_manual('ps -o pid,command -a -x -w -w -w');
     if ($err) {
       return $results;
     }
 
     $processes = array_filter(explode("\n", trim($processes)));
     foreach ($processes as $process) {
       list($pid, $command) = preg_split('/\s+/', trim($process), 2);
 
       $pattern = '/((launch|exec)_daemon.php|phd-daemon)/';
       $matches = null;
       if (!preg_match($pattern, $command, $matches)) {
         continue;
       }
 
       switch ($matches[1]) {
         case 'exec_daemon.php':
           $type = 'daemon';
           break;
         case 'launch_daemon.php':
         case 'phd-daemon':
         default:
           $type = 'overseer';
           break;
       }
 
       $results[(int)$pid] = array(
         'type' => $type,
         'command' => $command,
         'pid' => (int) $pid,
       );
     }
 
     return $results;
   }
 
+  private function updatePidfile() {
+    if (!$this->piddir) {
+      return;
+    }
+
+    $daemons = array();
+
+    foreach ($this->daemons as $daemon) {
+      $handle = $daemon['handle'];
+      $config = $daemon['config'];
+
+      if (!$handle->isRunning()) {
+        continue;
+      }
+
+      $daemons[] = array(
+        'pid' => $handle->getPID(),
+        'id' => $handle->getDaemonID(),
+        'config' => $config,
+      );
+    }
+
+    $pidfile = array(
+      'pid' => getmypid(),
+      'start' => $this->startEpoch,
+      'config' => $this->config,
+      'daemons' => $daemons,
+    );
+
+    if ($pidfile !== $this->lastPidfile) {
+      $this->lastPidfile = $pidfile;
+      $pidfile_path = $this->piddir.'/daemon.'.getmypid();
+      Filesystem::writeFile($pidfile_path, json_encode($pidfile));
+    }
+  }
+
 }