Index: src/__phutil_library_map__.php
===================================================================
--- src/__phutil_library_map__.php
+++ src/__phutil_library_map__.php
@@ -98,6 +98,7 @@
     'ArcanistEventType' => 'events/constant/ArcanistEventType.php',
     'ArcanistExitExpressionXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistExitExpressionXHPASTLinterRule.php',
     'ArcanistExportWorkflow' => 'workflow/ArcanistExportWorkflow.php',
+    'ArcanistExternalJsonLinter' => 'lint/linter/ArcanistExternalJsonLinter.php',
     'ArcanistExternalLinter' => 'lint/linter/ArcanistExternalLinter.php',
     'ArcanistExternalLinterTestCase' => 'lint/linter/__tests__/ArcanistExternalLinterTestCase.php',
     'ArcanistExtractUseXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistExtractUseXHPASTLinterRule.php',
@@ -393,6 +394,7 @@
     'ArcanistEventType' => 'PhutilEventType',
     'ArcanistExitExpressionXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistExportWorkflow' => 'ArcanistWorkflow',
+    'ArcanistExternalJsonLinter' => 'ArcanistLinter',
     'ArcanistExternalLinter' => 'ArcanistFutureLinter',
     'ArcanistExternalLinterTestCase' => 'ArcanistLinterTestCase',
     'ArcanistExtractUseXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
Index: src/lint/linter/ArcanistExternalJsonLinter.php
===================================================================
--- /dev/null
+++ src/lint/linter/ArcanistExternalJsonLinter.php
@@ -0,0 +1,272 @@
+<?php
+
+/**
+ * Simple glue linter which runs some script on each path and parses
+ * lint violations emitted by the script in JSON format.
+ *
+ * Configure this linter by setting these keys in your .arclint section:
+ *
+ *  - `external-json.script` Script command to run. This can be
+ *    the path to a linter script, but may also include flags or use shell
+ *    features (see below for examples).
+ *
+ * The script will be invoked from the project root, so you can specify a
+ * relative path like `scripts/lint.sh` or an absolute path like
+ * `/opt/lint/lint.sh`.
+ *
+ * This linter is necessarily more limited in its capabilities than a normal
+ * linter which can perform custom processing, but may be somewhat simpler to
+ * configure.
+ *
+ * == Script and JSON format ==
+ *
+ * The script will be invoked once for each file that is to be linted, with
+ * the file passed as the first argument. The file may begin with a "-"; ensure
+ * your script will not interpret such files as flags (perhaps by ending your
+ * script configuration with "--", if its argument parser supports that).
+ *
+ * Note that when run via `arc diff`, the list of files to be linted includes
+ * deleted files and files that were moved away by the change. The linter should
+ * not assume the path it is given exists, and it is not an error for the
+ * linter to be invoked with paths which are no longer there. (Every affected
+ * path is subject to lint because some linters may raise errors in other files
+ * when a file is removed, or raise an error about its removal.)
+ *
+ * The script should emit a JSON array of lint violations to stdout. A lint
+ * violation may have the following attributes,
+ *
+ *   - `message` (required) Text describing the lint message. For example,
+ *     "This is a syntax error.".
+ *   - `name` (optional) Text summarizing the lint message. For example,
+ *     "Syntax Error".
+ *   - `severity` (optional) The word "error", "warning", "autofix", "advice",
+ *     or "disabled", in any combination of upper and lower case. Instead, you
+ *   - `file` (optional) The name of the file to raise the lint message in. If
+ *     not specified, defaults to the linted file. It is generally not necessary
+ *     to specify this unless the linter can raise messages in files other than
+ *     the one it is linting.
+ *   - `line` (optional) The line number of the message.
+ *   - `char` (optional) The character offset of the message.
+ *   - `offset` (optional) The byte offset of the message. If provided, this
+ *     supersedes `line` and `char`.
+ *   - `original` (optional) The text the message affects.
+ *   - `replacement` (optional) The text that the range captured by `original`
+ *     should be automatically replaced by to resolve the message.
+ *   - `code` (optional) A short error type identifier which can be used
+ *     elsewhere to configure handling of specific types of messages. For
+ *     example, "EXAMPLE1", "EXAMPLE2", etc., where each code identifies a
+ *     class of message like "syntax error", "missing whitespace", etc. This
+ *     allows configuration to later change the severity of all whitespace
+ *     messages, for example.
+ *   - `throw` (optional) If set with a string error message `arc` will throw
+ *     the given message. You can use this to fail abruptly if you
+ *     encounter unexpected output. All processing will abort.
+ *
+ * For example, the following would encode a warning and an error,
+ *
+ *   [ { 'message': 'Too many goats!', 'line': 13, 'severity': 'error' }
+ *   , { 'message': 'Not enough boats.', 'line': 22, 'severity: 'warning' }
+ *   ]
+ *
+ * @task  lint        Linting
+ * @task  linterinfo  Linter Information
+ * @task  parse       Parsing Output
+ * @task  config      Validating Configuration
+ */
+final class ArcanistExternalJsonLinter extends ArcanistLinter {
+
+  private $script = null;
+  private $output = array();
+
+  public function getInfoName() {
+    return pht('External JSON');
+  }
+
+  public function getInfoDescription() {
+    return pht(
+      'Run an external script, then parse its output as a JSON document'.
+      'describing the lint violations. This is a generic binding that can '.
+      'be used to run custom lint scripts.');
+  }
+
+  protected function shouldLintBinaryFiles() {
+    return true;
+  }
+
+  protected function shouldLintDeletedFiles() {
+    return true;
+  }
+
+  protected function shouldLintDirectories() {
+    return true;
+  }
+
+  protected function shouldLintSymbolicLinks() {
+    return true;
+  }
+
+
+/* -(  Linting  )------------------------------------------------------------ */
+
+
+  /**
+   * Run the script on each file to be linted.
+   *
+   * @task lint
+   */
+  public function willLintPaths(array $paths) {
+    $root = $this->getProjectRoot();
+
+    $futures = array();
+    foreach ($paths as $path) {
+      $future = new ExecFuture('%C %s', $this->script, $path);
+      $future->setCWD($root);
+      $futures[$path] = $future;
+    }
+
+    $futures = id(new FutureIterator($futures))
+      ->limit(4);
+    foreach ($futures as $path => $future) {
+      list($stdout) = $future->resolvex();
+      $this->output[$path] = $stdout;
+    }
+  }
+
+  /**
+   * Run the regex on the output of the script.
+   *
+   * @task lint
+   */
+  public function lintPath($path) {
+    $output = idx($this->output, $path);
+    if (!strlen($output)) {
+      // No output, but it exited 0, so just move on.
+      return;
+    }
+
+    $messages = json_decode($output, true);
+
+    foreach ($messages as $message) {
+      if (!empty($message['throw'])) {
+          $throw = $message['throw'];
+          throw new ArcanistUsageException(
+            pht(
+              "%s: linter threw an exception: '%s'\n",
+              __CLASS__,
+              $throw));
+      }
+
+      $line = idx($message, 'line');
+      if ($line) {
+        $line = (int)$line;
+      } else {
+        $line = null;
+      }
+      $char = idx($message, 'char');
+      if ($char) {
+          $char = (int)$char;
+      } else {
+          $char = null;
+      }
+
+      $dict = array(
+        'path'        => idx($message, 'file', $path),
+        'line'        => $line,
+        'char'        => $char,
+        'code'        => idx($message, 'code', $this->getLinterName()),
+        'severity'    => $this->getMessageSeverity($message),
+        'name'        => idx($message, 'name', 'Lint'),
+        'description' => idx($message, 'message',
+                             pht('Undefined Lint Message')),
+      );
+
+      $original = idx($message, 'original');
+      if ($original !== null) {
+        $dict['original'] = $original;
+      }
+
+      $replacement = idx($message, 'replacement');
+      if ($replacement !== null) {
+        $dict['replacement'] = $replacement;
+      }
+
+      $lint = ArcanistLintMessage::newFromDictionary($dict);
+      $this->addLintMessage($lint);
+    }
+  }
+
+
+/* -(  Linter Information  )------------------------------------------------- */
+
+  /**
+   * Return the short name of the linter.
+   *
+   * @return string Short linter identifier.
+   *
+   * @task linterinfo
+   */
+  public function getLinterName() {
+    return 'ExtJson';
+  }
+
+  public function getLinterConfigurationName() {
+    return 'external-json';
+  }
+
+  public function getLinterConfigurationOptions() {
+    // These fields are optional only to avoid breaking things.
+    $options = array(
+      'external-json.script' => array(
+        'type' => 'string',
+        'help' => pht('Script to execute.'),
+      ),
+    );
+
+    return $options + parent::getLinterConfigurationOptions();
+  }
+
+  public function setLinterConfigurationValue($key, $value) {
+    switch ($key) {
+      case 'external-json.script':
+        $this->script = $value;
+        return;
+    }
+
+    return parent::setLinterConfigurationValue($key, $value);
+  }
+
+/* -(  Parsing Output  )----------------------------------------------------- */
+
+  /**
+   * Map the regex matching groups to a message severity. We look for either
+   * a nonempty severity name group like 'error', or a group called 'severity'
+   * with a valid name.
+   *
+   * @param dict message object
+   * @return const  @{class:ArcanistLintSeverity} constant.
+   *
+   * @task parse
+   */
+  private function getMessageSeverity(array $message) {
+    $map = array(
+      'error'    => ArcanistLintSeverity::SEVERITY_ERROR,
+      'warning'  => ArcanistLintSeverity::SEVERITY_WARNING,
+      'autofix'  => ArcanistLintSeverity::SEVERITY_AUTOFIX,
+      'advice'   => ArcanistLintSeverity::SEVERITY_ADVICE,
+      'disabled' => ArcanistLintSeverity::SEVERITY_DISABLED,
+    );
+
+    if (idx($message, 'severity')) {
+      $severity_name = strtolower(idx($message, 'severity'));
+      if (!idx($map, $severity_name)) {
+        throw new ArcanistUsageException(
+          pht('%s: Unknown severity %s', __CLASS__, $severity_name));
+      } else {
+        return $map[$severity_name];
+      }
+    } else {
+      return ArcanistLintSeverity::SEVERITY_ERROR;
+    }
+  }
+
+}