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
@@ -2938,6 +2938,7 @@
     'PhabricatorFileUploadDialogController' => 'applications/files/controller/PhabricatorFileUploadDialogController.php',
     'PhabricatorFileUploadException' => 'applications/files/exception/PhabricatorFileUploadException.php',
     'PhabricatorFileUploadSource' => 'applications/files/uploadsource/PhabricatorFileUploadSource.php',
+    'PhabricatorFileUploadSourceByteLimitException' => 'applications/files/uploadsource/PhabricatorFileUploadSourceByteLimitException.php',
     'PhabricatorFileinfoSetupCheck' => 'applications/config/check/PhabricatorFileinfoSetupCheck.php',
     'PhabricatorFilesApplication' => 'applications/files/application/PhabricatorFilesApplication.php',
     'PhabricatorFilesApplicationStorageEnginePanel' => 'applications/files/applicationpanel/PhabricatorFilesApplicationStorageEnginePanel.php',
@@ -8362,6 +8363,7 @@
     'PhabricatorFileUploadDialogController' => 'PhabricatorFileController',
     'PhabricatorFileUploadException' => 'Exception',
     'PhabricatorFileUploadSource' => 'Phobject',
+    'PhabricatorFileUploadSourceByteLimitException' => 'Exception',
     'PhabricatorFileinfoSetupCheck' => 'PhabricatorSetupCheck',
     'PhabricatorFilesApplication' => 'PhabricatorApplication',
     'PhabricatorFilesApplicationStorageEnginePanel' => 'PhabricatorApplicationConfigurationPanel',
diff --git a/src/applications/diffusion/query/DiffusionFileFutureQuery.php b/src/applications/diffusion/query/DiffusionFileFutureQuery.php
--- a/src/applications/diffusion/query/DiffusionFileFutureQuery.php
+++ b/src/applications/diffusion/query/DiffusionFileFutureQuery.php
@@ -88,7 +88,7 @@
   }
 
   final protected function executeQuery() {
-    $future = $this->newQueryFuture();
+    $future = $this->newConfiguredQueryFuture();
 
     $drequest = $this->getRequest();
 
@@ -105,6 +105,11 @@
         ->setViewPolicy(PhabricatorPolicies::POLICY_NOONE)
         ->setExecFuture($future);
 
+      $byte_limit = $this->getByteLimit();
+      if ($byte_limit) {
+        $source->setByteLimit($byte_limit);
+      }
+
       $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
         $file = $source->uploadFile();
       unset($unguarded);
@@ -116,18 +121,8 @@
 
       $this->didHitTimeLimit = true;
       $file = null;
-    }
-
-    $byte_limit = $this->getByteLimit();
-
-    if ($byte_limit && ($file->getByteSize() > $byte_limit)) {
+    } catch (PhabricatorFileUploadSourceByteLimitException $ex) {
       $this->didHitByteLimit = true;
-
-      $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
-        id(new PhabricatorDestructionEngine())
-          ->destroyObject($file);
-      unset($unguarded);
-
       $file = null;
     }
 
@@ -141,11 +136,6 @@
       $future->setTimeout($this->getTimeout());
     }
 
-    $byte_limit = $this->getByteLimit();
-    if ($byte_limit) {
-      $future->setStdoutSizeLimit($byte_limit + 1);
-    }
-
     return $future;
   }
 
diff --git a/src/applications/files/uploadsource/PhabricatorFileUploadSource.php b/src/applications/files/uploadsource/PhabricatorFileUploadSource.php
--- a/src/applications/files/uploadsource/PhabricatorFileUploadSource.php
+++ b/src/applications/files/uploadsource/PhabricatorFileUploadSource.php
@@ -12,6 +12,8 @@
   private $shouldChunk;
   private $didRewind;
   private $totalBytesWritten = 0;
+  private $totalBytesRead = 0;
+  private $byteLimit = 0;
 
   public function setName($name) {
     $this->name = $name;
@@ -40,6 +42,15 @@
     return $this->viewPolicy;
   }
 
+  public function setByteLimit($byte_limit) {
+    $this->byteLimit = $byte_limit;
+    return $this;
+  }
+
+  public function getByteLimit() {
+    return $this->byteLimit;
+  }
+
   public function uploadFile() {
     if (!$this->shouldChunkFile()) {
       return $this->writeSingleFile();
@@ -81,8 +92,15 @@
       return false;
     }
 
+    $read_bytes = $data->current();
+    $this->totalBytesRead += strlen($read_bytes);
+
+    if ($this->byteLimit && ($this->totalBytesRead > $this->byteLimit)) {
+      throw new PhabricatorFileUploadSourceByteLimitException();
+    }
+
     $rope = $this->getRope();
-    $rope->append($data->current());
+    $rope->append($read_bytes);
 
     return true;
   }
@@ -160,8 +178,10 @@
       }
     }
 
-    // If we have extra bytes at the end, write them.
-    if ($rope->getByteLength()) {
+    // If we have extra bytes at the end, write them. Note that it's possible
+    // that we have more than one chunk of bytes left if the read was very
+    // fast.
+    while ($rope->getByteLength()) {
       $this->writeChunk($file, $engine);
     }
 
diff --git a/src/applications/files/uploadsource/PhabricatorFileUploadSourceByteLimitException.php b/src/applications/files/uploadsource/PhabricatorFileUploadSourceByteLimitException.php
new file mode 100644
--- /dev/null
+++ b/src/applications/files/uploadsource/PhabricatorFileUploadSourceByteLimitException.php
@@ -0,0 +1,4 @@
+<?php
+
+final class PhabricatorFileUploadSourceByteLimitException
+  extends Exception {}