diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 5235f69a..24957b24 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -69,6 +69,8 @@ phutil_register_library_map(array(
     'ArcanistExternalLinter' => 'lint/linter/ArcanistExternalLinter.php',
     'ArcanistExternalLinterTestCase' => 'lint/linter/__tests__/ArcanistExternalLinterTestCase.php',
     'ArcanistFeatureWorkflow' => 'workflow/ArcanistFeatureWorkflow.php',
+    'ArcanistFileDataRef' => 'upload/ArcanistFileDataRef.php',
+    'ArcanistFileUploader' => 'upload/ArcanistFileUploader.php',
     'ArcanistFilenameLinter' => 'lint/linter/ArcanistFilenameLinter.php',
     'ArcanistFilenameLinterTestCase' => 'lint/linter/__tests__/ArcanistFilenameLinterTestCase.php',
     'ArcanistFlagWorkflow' => 'workflow/ArcanistFlagWorkflow.php',
@@ -258,6 +260,8 @@ phutil_register_library_map(array(
     'ArcanistExternalLinter' => 'ArcanistFutureLinter',
     'ArcanistExternalLinterTestCase' => 'ArcanistLinterTestCase',
     'ArcanistFeatureWorkflow' => 'ArcanistWorkflow',
+    'ArcanistFileDataRef' => 'Phobject',
+    'ArcanistFileUploader' => 'Phobject',
     'ArcanistFilenameLinter' => 'ArcanistLinter',
     'ArcanistFilenameLinterTestCase' => 'ArcanistLinterTestCase',
     'ArcanistFlagWorkflow' => 'ArcanistWorkflow',
diff --git a/src/upload/ArcanistFileDataRef.php b/src/upload/ArcanistFileDataRef.php
new file mode 100644
index 00000000..053c6b57
--- /dev/null
+++ b/src/upload/ArcanistFileDataRef.php
@@ -0,0 +1,289 @@
+<?php
+
+/**
+ * Reference to a file or block of file data which can be uploaded using
+ * @{class:ArcanistFileUploader}.
+ *
+ * You can either upload a file on disk by using @{method:setPath}, or upload
+ * a block of data in memory by using @{method:setData}.
+ *
+ * For usage examples, see @{class:ArcanistFileUploader}.
+ *
+ * After uploading, successful uploads will have @{method:getPHID} populated.
+ * Failed uploads will have @{method:getErrors} populated with a description
+ * of reasons for failure.
+ *
+ * @task config Configuring File References
+ * @task results Handling Upload Results
+ * @task uploader Uploader API
+ */
+final class ArcanistFileDataRef extends Phobject {
+
+  private $name;
+  private $data;
+  private $path;
+  private $hash;
+  private $size;
+  private $errors = array();
+  private $phid;
+  private $fileHandle;
+
+
+/* -(  Configuring File References  )---------------------------------------- */
+
+
+  /**
+   * @task config
+   */
+  public function setName($name) {
+    $this->name = $name;
+    return $this;
+  }
+
+
+  /**
+   * @task config
+   */
+  public function getName() {
+    return $this->name;
+  }
+
+
+  /**
+   * @task config
+   */
+  public function setData($data) {
+    $this->data = $data;
+    return $this;
+  }
+
+
+  /**
+   * @task config
+   */
+  public function getData() {
+    return $this->data;
+  }
+
+
+  /**
+   * @task config
+   */
+  public function setPath($path) {
+    $this->path = $path;
+    return $this;
+  }
+
+
+  /**
+   * @task config
+   */
+  public function getPath() {
+    return $this->path;
+  }
+
+
+/* -(  Handling Upload Results  )-------------------------------------------- */
+
+
+  /**
+   * @task results
+   */
+  public function getErrors() {
+    return $this->errors;
+  }
+
+
+  /**
+   * @task results
+   */
+  public function getPHID() {
+    return $this->phid;
+  }
+
+
+/* -(  Uploader API  )------------------------------------------------------- */
+
+
+  /**
+   * @task uploader
+   */
+  public function willUpload() {
+    $have_data = ($this->data !== null);
+    $have_path = ($this->path !== null);
+
+    if (!$have_data && !$have_path) {
+      throw new Exception(
+        pht(
+          'Specify setData() or setPath() when building a file data '.
+          'reference.'));
+    }
+
+    if ($have_data && $have_path) {
+      throw new Exception(
+        pht(
+          'Specify either setData() or setPath() when building a file data '.
+          'reference, but not both.'));
+    }
+
+    if ($have_path) {
+      $path = $this->path;
+
+      if (!Filesystem::pathExists($path)) {
+        throw new Exception(
+          pht(
+            'Unable to upload file: path "%s" does not exist.',
+            $path));
+      }
+
+      try {
+        Filesystem::assertIsFile($path);
+      } catch (FilesystemException $ex) {
+        throw new Exception(
+          pht(
+            'Unable to upload file: path "%s" is not a file.',
+            $path));
+      }
+
+      try {
+        Filesystem::assertReadable($path);
+      } catch (FilesystemException $ex) {
+        throw new Exception(
+          pht(
+            'Unable to upload file: path "%s" is not readable.',
+            $path));
+      }
+
+      $hash = @sha1_file($path);
+      if ($hash === false) {
+        throw new Exception(
+          pht(
+            'Unable to upload file: failed to calculate file data hash for '.
+            'path "%s".',
+            $path));
+      }
+
+      $size = @filesize($path);
+      if ($size === false) {
+        throw new Exception(
+          pht(
+            'Unable to upload file: failed to determine filesize of '.
+            'path "%s".',
+            $path));
+      }
+
+      $this->hash = $hash;
+      $this->size = $size;
+    } else {
+      $data = $this->data;
+      $this->hash = sha1($data);
+      $this->size = strlen($data);
+    }
+  }
+
+
+  /**
+   * @task uploader
+   */
+  public function didFail($error) {
+    $this->errors[] = $error;
+    return $this;
+  }
+
+
+  /**
+   * @task uploader
+   */
+  public function setPHID($phid) {
+    $this->phid = $phid;
+    return $this;
+  }
+
+
+  /**
+   * @task uploader
+   */
+  public function getByteSize() {
+    if ($this->size === null) {
+      throw new PhutilInvalidStateException('willUpload');
+    }
+    return $this->size;
+  }
+
+
+  /**
+   * @task uploader
+   */
+  public function getContentHash() {
+    if ($this->size === null) {
+      throw new PhutilInvalidStateException('willUpload');
+    }
+    return $this->hash;
+  }
+
+
+  /**
+   * @task uploader
+   */
+  public function didUpload() {
+    if ($this->fileHandle) {
+      @fclose($this->fileHandle);
+      $this->fileHandle = null;
+    }
+  }
+
+
+  /**
+   * @task uploader
+   */
+  public function readBytes($start, $end) {
+    if ($this->size === null) {
+      throw new PhutilInvalidStateException('willUpload');
+    }
+
+    $len = ($end - $start);
+
+    if ($this->data !== null) {
+      return substr($this->data, $start, $len);
+    }
+
+    $path = $this->path;
+
+    if ($this->fileHandle === null) {
+      $f = @fopen($path, 'rb');
+      if (!$f) {
+        throw new Exception(
+          pht(
+            'Unable to upload file: failed to open path "%s" for reading.',
+            $path));
+      }
+      $this->fileHandle = $f;
+    }
+
+    $f = $this->fileHandle;
+
+    $ok = @fseek($f, $start);
+    if ($ok !== 0) {
+      throw new Exception(
+        pht(
+          'Unable to upload file: failed to fseek() to offset %d in file '.
+          'at path "%s".',
+          $start,
+          $path));
+    }
+
+    $data = @fread($f, $len);
+    if ($data === false) {
+      throw new Exception(
+        pht(
+          'Unable to upload file: failed to read %d bytes after offset %d '.
+          'from file at path "%s".',
+          $len,
+          $start,
+          $path));
+    }
+
+    return $data;
+  }
+
+}
diff --git a/src/upload/ArcanistFileUploader.php b/src/upload/ArcanistFileUploader.php
new file mode 100644
index 00000000..a9104d7b
--- /dev/null
+++ b/src/upload/ArcanistFileUploader.php
@@ -0,0 +1,257 @@
+<?php
+
+/**
+ * Upload a list of @{class:ArcanistFileDataRef} objects over Conduit.
+ *
+ *   // Create a new uploader.
+ *   $uploader = id(new ArcanistFileUploader())
+ *     ->setConduitClient($conduit);
+ *
+ *   // Queue one or more files to be uploaded.
+ *   $file = id(new ArcanistFileDataRef())
+ *     ->setName('example.jpg')
+ *     ->setPath('/path/to/example.jpg');
+ *   $uploader->addFile($file);
+ *
+ *   // Upload the files.
+ *   $files = $uploader->uploadFiles();
+ *
+ * For details about building file references, see @{class:ArcanistFileDataRef}.
+ *
+ * @task config Configuring the Uploader
+ * @task add Adding Files
+ * @task upload Uploading Files
+ * @task internal Internals
+ */
+final class ArcanistFileUploader extends Phobject {
+
+  private $conduit;
+  private $files;
+
+
+/* -(  Configuring the Uploader  )------------------------------------------- */
+
+
+  /**
+   * @task config
+   */
+  public function setConduitClient(ConduitClient $conduit) {
+    $this->conduit = $conduit;
+    return $this;
+  }
+
+
+/* -(  Adding Files  )------------------------------------------------------- */
+
+
+  /**
+   * @task add
+   */
+  public function addFile(ArcanistFileDataRef $file) {
+    $this->files[] = $file;
+    return $this;
+  }
+
+
+/* -(  Uploading Files  )---------------------------------------------------- */
+
+
+  /**
+   * @task upload
+   */
+  public function uploadFiles() {
+    if (!$this->conduit) {
+      throw new PhutilInvalidStateException('setConduitClient');
+    }
+
+    $files = $this->files;
+    foreach ($files as $key => $file) {
+      try {
+        $file->willUpload();
+      } catch (Exception $ex) {
+        $file->didFail($ex->getMessage());
+        unset($files[$key]);
+      }
+    }
+
+    $conduit = $this->conduit;
+    $futures = array();
+    foreach ($files as $key => $file) {
+      $futures[$key] = $conduit->callMethod(
+        'file.allocate',
+        array(
+          'name' => $file->getName(),
+          'contentLength' => $file->getByteSize(),
+          'contentHash' => $file->getContentHash(),
+        ));
+    }
+
+    $iterator = id(new FutureIterator($futures))->limit(4);
+    $chunks = array();
+    foreach ($iterator as $key => $future) {
+      try {
+        $result = $future->resolve();
+      } catch (Exception $ex) {
+        // The most likely cause for a failure here is that the server does
+        // not support `file.allocate`. In this case, we'll try the older
+        // upload method below.
+        continue;
+      }
+
+      $phid = $result['filePHID'];
+      $file = $files[$key];
+
+      // We don't need to upload any data. Figure out why not: this can either
+      // be because of an error (server can't accept the data) or because the
+      // server already has the data.
+      if (!$result['upload']) {
+        if (!$phid) {
+          $file->didFail(
+            pht(
+              'Unable to upload file: the server refused to accept file '.
+              '"%s". This usually means it is too large.',
+              $file->getName()));
+        } else {
+          // These server completed the upload by creating a reference to known
+          // file data. We don't need to transfer the actual data, and are all
+          // set.
+          $file->setPHID($phid);
+        }
+        unset($files[$key]);
+        continue;
+      }
+
+      // The server wants us to do an upload.
+      if ($phid) {
+        $chunks[$key] = array(
+          'file' => $file,
+          'phid' => $phid,
+        );
+      }
+    }
+
+    foreach ($chunks as $key => $chunk) {
+      $file = $chunk['file'];
+      $phid = $chunk['phid'];
+      try {
+        $this->uploadChunks($file, $phid);
+        $file->setPHID($phid);
+      } catch (Exception $ex) {
+        $file->didFail(
+          pht(
+            'Unable to upload file chunks: %s',
+            $ex->getMessage()));
+      }
+      unset($files[$key]);
+    }
+
+    foreach ($files as $key => $file) {
+      try {
+        $phid = $this->uploadData($file);
+        $file->setPHID($phid);
+      } catch (Exception $ex) {
+        $file->didFail(
+          pht(
+            'Unable to upload file data: %s',
+            $ex->getMessage()));
+      }
+      unset($files[$key]);
+    }
+
+    foreach ($this->files as $file) {
+      $file->didUpload();
+    }
+
+    return $this->files;
+  }
+
+
+/* -(  Internals  )---------------------------------------------------------- */
+
+
+  /**
+   * @task internal
+   */
+  private function uploadChunks(ArcanistFileDataRef $file, $file_phid) {
+    $conduit = $this->conduit;
+
+    $chunks = $conduit->callMethodSynchronous(
+      'file.querychunks',
+      array(
+        'filePHID' => $file_phid,
+      ));
+
+    $remaining = array();
+    foreach ($chunks as $chunk) {
+      if (!$chunk['complete']) {
+        $remaining[] = $chunk;
+      }
+    }
+
+    $done = (count($chunks) - count($remaining));
+
+    if ($done) {
+      $this->writeStatus(
+        pht(
+          'Resuming upload (%d of %d chunks remain).',
+          new PhutilNumber(count($remaining)),
+          new PhutilNumber(count($chunks))));
+    } else {
+      $this->writeStatus(
+        pht(
+          'Uploading chunks (%d chunks to upload).',
+          new PhutilNumber(count($remaining))));
+    }
+
+    $progress = new PhutilConsoleProgressBar();
+    $progress->setTotal(count($chunks));
+
+    for ($ii = 0; $ii < $done; $ii++) {
+      $progress->update(1);
+    }
+
+    $progress->draw();
+
+    // TODO: We could do these in parallel to improve upload performance.
+    foreach ($remaining as $chunk) {
+      $data = $file->readBytes($chunk['byteStart'], $chunk['byteEnd']);
+
+      $conduit->callMethodSynchronous(
+        'file.uploadchunk',
+        array(
+          'filePHID' => $file_phid,
+          'byteStart' => $chunk['byteStart'],
+          'dataEncoding' => 'base64',
+          'data' => base64_encode($data),
+        ));
+
+      $progress->update(1);
+    }
+  }
+
+
+  /**
+   * @task internal
+   */
+  private function uploadData(ArcanistFileDataRef $file) {
+    $conduit = $this->conduit;
+
+    $data = $file->readBytes(0, $file->getByteSize());
+
+    return $conduit->callMethodSynchronous(
+      'file.upload',
+      array(
+        'name' => $file->getName(),
+        'data_base64' => base64_encode($data),
+      ));
+  }
+
+
+  /**
+   * @task internal
+   */
+  private function writeStatus($message) {
+    echo $message."\n";
+  }
+
+}
diff --git a/src/workflow/ArcanistUploadWorkflow.php b/src/workflow/ArcanistUploadWorkflow.php
index b1c711cb..64c5260d 100644
--- a/src/workflow/ArcanistUploadWorkflow.php
+++ b/src/workflow/ArcanistUploadWorkflow.php
@@ -54,76 +54,28 @@ EOTEXT
     $conduit = $this->getConduit();
     $results = array();
 
+    $uploader = id(new ArcanistFileUploader())
+      ->setConduitClient($conduit);
+
     foreach ($this->paths as $path) {
-      $path = Filesystem::resolvePath($path);
+      $file = id(new ArcanistFileDataRef())
+        ->setName(basename($path))
+        ->setPath($path);
 
-      $name = basename($path);
-      $this->writeStatus(pht("Uploading '%s'...", $name));
+      $uploader->addFile($file);
+    }
 
-      $hash = @sha1_file($path);
-      if (!$hash) {
-        throw new Exception(pht('Unable to read file "%s"!', $path));
-      }
-      $length = filesize($path);
-
-      $do_chunk_upload = false;
-
-      $phid = null;
-      try {
-        $result = $conduit->callMethodSynchronous(
-          'file.allocate',
-          array(
-            'name' => $name,
-            'contentLength' => $length,
-            'contentHash' => $hash,
-          ));
-
-        $phid = $result['filePHID'];
-        if (!$result['upload']) {
-          if (!$phid) {
-            $this->writeStatus(
-              pht(
-                'Unable to upload file "%s": the server refused to accept '.
-                'it. This usually means it is too large.',
-                $name));
-            continue;
-          }
-          // Otherwise, the server completed the upload by referencing known
-          // file data.
-        } else {
-          if ($phid) {
-            $do_chunk_upload = true;
-          } else {
-            // This is a small file that doesn't need to be uploaded in
-            // chunks, so continue normally.
-          }
-        }
-      } catch (Exception $ex) {
-        $this->writeStatus(
-          pht('Unable to use allocate method, trying older upload method.'));
-      }
-
-      if ($do_chunk_upload) {
-        $this->uploadChunks($phid, $path);
-      }
-
-      if (!$phid) {
-        try {
-          $data = Filesystem::readFile($path);
-        } catch (FilesystemException $ex) {
-          $this->writeStatus(
-            pht('Unable to read file "%s".', $ex->getMessage()));
-          $results[$path] = null;
-          continue;
-        }
-
-        $phid = $conduit->callMethodSynchronous(
-          'file.upload',
-          array(
-            'data_base64' => base64_encode($data),
-            'name' => $name,
-          ));
+    $files = $uploader->uploadFiles();
+
+    $results = array();
+    foreach ($files as $file) {
+      // TODO: This could be handled more gracefully; just preserving behavior
+      // until we introduce `file.query` and modernize this.
+      if ($file->getErrors()) {
+        throw new Exception(implode("\n", $file->getErrors()));
       }
+      $phid = $file->getPHID();
+      $name = $file->getName();
 
       $info = $conduit->callMethodSynchronous(
         'file.info',