diff --git a/src/workflow/ArcanistBaseWorkflow.php b/src/workflow/ArcanistBaseWorkflow.php
--- a/src/workflow/ArcanistBaseWorkflow.php
+++ b/src/workflow/ArcanistBaseWorkflow.php
@@ -1124,10 +1124,10 @@
     }
 
     if (empty($this->changeCache[$path])) {
-      if ($is_git) {
-        // This can legitimately occur under git if you make a change, "git
-        // commit" it, and then revert the change in the working copy and run
-        // "arc lint".
+      if ($is_git || $is_hg) {
+        // This can legitimately occur under git/hg if you make a change,
+        // "git/hg commit" it, and then revert the change in the working copy
+        // and run "arc lint".
         $change = new ArcanistDiffChange();
         $change->setCurrentPath($path);
         return $change;
diff --git a/src/workflow/ArcanistDiffWorkflow.php b/src/workflow/ArcanistDiffWorkflow.php
--- a/src/workflow/ArcanistDiffWorkflow.php
+++ b/src/workflow/ArcanistDiffWorkflow.php
@@ -394,6 +394,11 @@
           'unit' => true,
         ),
       ),
+      'auto-convert-binary' => array(
+        'help' =>
+          'Mark file as binary without prompting in case that changes '.
+          'to a file exceed the size limit.',
+      ),
       '*' => 'paths',
     );
 
@@ -999,7 +1004,8 @@
           $confirm =
             "{$byte_warning} If the file is not a text file, you can ".
             "mark it 'binary'. Mark this file as 'binary' and continue?";
-          if (phutil_console_confirm($confirm)) {
+          if ($this->getArgument('auto-convert-binary') ||
+              phutil_console_confirm($confirm)) {
             $change->convertToBinaryChange($repository_api);
           } else {
             throw new ArcanistUsageException(