diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -365,6 +365,7 @@
     'PhutilProcessGroupDaemon' => 'daemon/torture/PhutilProcessGroupDaemon.php',
     'PhutilProcessQuery' => 'filesystem/PhutilProcessQuery.php',
     'PhutilProcessRef' => 'filesystem/PhutilProcessRef.php',
+    'PhutilProcessRefTestCase' => 'filesystem/__tests__/PhutilProcessRefTestCase.php',
     'PhutilProseDiff' => 'utils/PhutilProseDiff.php',
     'PhutilProseDiffTestCase' => 'utils/__tests__/PhutilProseDiffTestCase.php',
     'PhutilProseDifferenceEngine' => 'utils/PhutilProseDifferenceEngine.php',
@@ -1031,6 +1032,7 @@
     'PhutilProcessGroupDaemon' => 'PhutilTortureTestDaemon',
     'PhutilProcessQuery' => 'Phobject',
     'PhutilProcessRef' => 'Phobject',
+    'PhutilProcessRefTestCase' => 'PhutilTestCase',
     'PhutilProseDiff' => 'Phobject',
     'PhutilProseDiffTestCase' => 'PhutilTestCase',
     'PhutilProseDifferenceEngine' => 'Phobject',
diff --git a/src/filesystem/PhutilProcessQuery.php b/src/filesystem/PhutilProcessQuery.php
--- a/src/filesystem/PhutilProcessQuery.php
+++ b/src/filesystem/PhutilProcessQuery.php
@@ -36,13 +36,14 @@
       list($pid, $command) = $parts;
 
       $ref = id(new PhutilProcessRef())
-        ->setPID((int)$pid)
-        ->setCommand($command);
+        ->setPID((int)$pid);
+
+      $argv = $this->getArgv($pid, $command);
+      $ref->setArgv($argv);
 
       // If this process is a "phd-daemon" process, mark it as a daemon
       // overseer.
-      $is_overseer = (bool)preg_match('/\bphd-daemon\b/', $command);
-      $ref->setIsOverseer($is_overseer);
+      $is_overseer = $ref->getIsOverseer();
 
       // If this is an overseer and the command has a "-l" ("Label") argument,
       // the argument contains the "PHABRICATOR_INSTANCE" value for the daemon.
@@ -80,4 +81,49 @@
     return array_values($refs);
   }
 
+  private function getArgv($pid, $command) {
+
+    // In the output of "ps", arguments in process titles are not escaped, so
+    // we can not distinguish between the processes created by running these
+    // commands by looking only at the output of "ps":
+    //
+    //   echo 'a b'
+    //   echo a b
+    //
+    // Both commands will have the same process title in the output of "ps".
+
+    // This means we may split the command incorrectly in the general case,
+    // and this misparsing may be important if the process binary resides in
+    // a directory with spaces in its path and we're trying to identify which
+    // binary a process is running.
+
+    // On Ubuntu, and likely most other Linux systems, we can get a raw
+    // command line from "/proc" with arguments delimited by "\0".
+
+    // On macOS, there's no "/proc" and we don't currently have a robust way
+    // to split the process command in a way that parses spaces properly, so
+    // fall back to a best effort based on the output of "ps". This is almost
+    // always correct, since it is uncommon to put binaries under paths with
+    // spaces in them.
+
+    $proc_cmdline = sprintf('/proc/%d/cmdline', $pid);
+    try {
+      $argv = Filesystem::readFile($proc_cmdline);
+      $argv = explode("\0", $argv);
+
+      // The output itself is terminated with "\0", so remove the final empty
+      // argument.
+      if (last($argv) === '') {
+        array_pop($argv);
+      }
+
+      return $argv;
+    } catch (Exception $ex) {
+      // If we fail to read "/proc", fall through to less reliable methods.
+    }
+
+    // If we haven't found a better source, just split the "ps" output on
+    // spaces.
+    return preg_split('/\s+/', $command);
+  }
 }
diff --git a/src/filesystem/PhutilProcessRef.php b/src/filesystem/PhutilProcessRef.php
--- a/src/filesystem/PhutilProcessRef.php
+++ b/src/filesystem/PhutilProcessRef.php
@@ -7,6 +7,7 @@
   private $command;
   private $isOverseer;
   private $instance;
+  private $argv;
 
   public function setPID($pid) {
     $this->pid = $pid;
@@ -17,21 +18,23 @@
     return $this->pid;
   }
 
-  public function setCommand($command) {
-    $this->command = $command;
-    return $this;
-  }
-
   public function getCommand() {
-    return $this->command;
-  }
+    if (!$this->command) {
+      $this->command = phutil_string_cast(csprintf('%LR', $this->argv));
+    }
 
-  public function setIsOverseer($is_overseer) {
-    $this->isOverseer = $is_overseer;
-    return $this;
+    return $this->command;
   }
 
   public function getIsOverseer() {
+    if ($this->isOverseer === null) {
+      $this->isOverseer = $this->getCommandMatch(
+        array(
+          array('phd-daemon'),
+          array('php', 'phd-daemon'),
+        ));
+    }
+
     return $this->isOverseer;
   }
 
@@ -44,4 +47,34 @@
     return $this->instance;
   }
 
+  private function getCommandMatch(array $patterns) {
+    $argv = $this->getArgv();
+
+    foreach ($patterns as $pattern) {
+      $pattern = array_values($pattern);
+      $is_match = true;
+      for ($ii = 0; $ii < count($pattern); $ii++) {
+        if (basename($argv[$ii]) !== $pattern[$ii]) {
+          $is_match = false;
+          break;
+        }
+      }
+
+      if ($is_match) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  public function setArgv(array $argv) {
+    $this->argv = $argv;
+    return $this;
+  }
+
+  public function getArgv() {
+    return $this->argv;
+  }
+
 }
diff --git a/src/filesystem/__tests__/PhutilProcessRefTestCase.php b/src/filesystem/__tests__/PhutilProcessRefTestCase.php
new file mode 100644
--- /dev/null
+++ b/src/filesystem/__tests__/PhutilProcessRefTestCase.php
@@ -0,0 +1,59 @@
+<?php
+
+final class PhutilProcessRefTestCase
+  extends PhutilTestCase {
+
+  public function testIdentifyOverseerProcess() {
+
+    // Test if various process argument vectors are correclty identified as
+    // daemon overseer processes or not. We're hoping to identify legitimate
+    // daemons and ignore false positives for processes with titles that look
+    // similar but are not really daemons, like "grep phd-daemon".
+
+    $tests = array(
+      array(
+        array('php', 'phd-daemon'),
+        true,
+      ),
+      array(
+        array('/path/to/php', '/path/to/phd-daemon'),
+        true,
+      ),
+      array(
+        array('/path/to/phd-daemon'),
+        true,
+      ),
+      array(
+        array('phd-daemon'),
+        true,
+      ),
+      array(
+        array('php', 'phd-daemon', '-l', 'instance-label'),
+        true,
+      ),
+      array(
+        array('grep phd-daemon'),
+        false,
+      ),
+      array(
+        array('this-is-a-phd-daemon'),
+        false,
+      ),
+    );
+
+    foreach ($tests as $case) {
+      list($argv, $expect) = $case;
+
+      $ref = id(new PhutilProcessRef())
+        ->setArgv($argv);
+
+      $actual = $ref->getIsOverseer();
+
+      $this->assertEqual(
+        $expect,
+        $actual,
+        pht('argv: %s', implode(' ', $argv)));
+    }
+  }
+
+}