diff --git a/src/S3/Transfer.php b/src/S3/Transfer.php
index 7679950b4e..01a0205c35 100644
--- a/src/S3/Transfer.php
+++ b/src/S3/Transfer.php
@@ -25,6 +25,7 @@ class Transfer implements PromisorInterface
     private $sourceMetadata;
     private $destination;
     private $concurrency;
+    private $partSize;
     private $mupThreshold;
     private $before;
     private $after;
@@ -118,6 +119,9 @@ public function __construct(
         $this->concurrency = isset($options['concurrency'])
             ? $options['concurrency']
             : MultipartUploader::DEFAULT_CONCURRENCY;
+        $this->partSize = isset($options['part_size'])
+            ? $options['part_size']
+            : MultipartUploader::PART_MIN_SIZE;
         $this->mupThreshold = isset($options['mup_threshold'])
             ? $options['mup_threshold']
             : 16777216;
@@ -387,6 +391,7 @@ private function uploadMultipart($filename)
             'before_upload'   => $this->before,
             'before_complete' => $this->before,
             'concurrency'     => $this->concurrency,
+            'part_size'       => $this->partSize,
             'add_content_md5' => $this->addContentMD5
         ]))->promise();
     }
diff --git a/tests/S3/TransferTest.php b/tests/S3/TransferTest.php
index 7007e67a15..9e07f90b86 100644
--- a/tests/S3/TransferTest.php
+++ b/tests/S3/TransferTest.php
@@ -253,6 +253,40 @@ public function testDoesMultipartForLargeFilesWithFileInfoAsSource()
         `rm -rf $dir`;
     }
 
+    public function testMultipartForLargeFilesDoesUsePartSize()
+    {
+        $s3 = $this->getTestClient('s3');
+        $this->addMockResults($s3, [
+            new Result(['UploadId' => '123']),
+            new Result(['ETag' => 'a']),
+            new Result(['ETag' => 'b']),
+            new Result(['UploadId' => '123']),
+        ]);
+
+        $dir = sys_get_temp_dir() . '/unittest';
+        `rm -rf $dir`;
+        mkdir($dir);
+        $filename = new SplFileInfo($dir . '/large.txt');
+        $f = fopen($filename, 'w+');
+        $line = str_repeat('.', 1024);
+        for ($i = 0; $i < 20000; $i++) {
+            fwrite($f, $line);
+        }
+        fclose($f);
+
+        $res = fopen('php://temp', 'r+');
+        $t = new Transfer($s3, $dir, 's3://foo/bar', [
+            'part_size' => 1024 * 1024 * 10,
+            'debug' => $res
+        ]);
+
+        $t->transfer();
+        rewind($res);
+        $output = stream_get_contents($res);
+        $this->assertStringNotContainsString("Transferring $filename -> s3://foo/bar/large.txt (UploadPart) : Part=3", $output);
+        `rm -rf $dir`;
+    }
+
     public function testDownloadsObjects()
     {
         $s3 = $this->getTestClient('s3');