diff -r 0e8743a6924e Lib/shutil.py
--- a/Lib/shutil.py	Sat Oct 31 12:23:03 2015 +0000
+++ b/Lib/shutil.py	Sat Oct 31 17:10:08 2015 +0100
@@ -113,7 +113,44 @@
     else:
         with open(src, 'rb') as fsrc:
             with open(dst, 'wb') as fdst:
-                copyfileobj(fsrc, fdst)
+                done = False
+                if hasattr(os, 'sendfile'):
+                    # Prefer os.sendfile if available for performance
+                    max_bcount = 2 ** 31 - 1
+                    bcount = max_bcount
+                    offset = 0
+                    fdstno = fdst.fileno()
+                    fsrcno = fsrc.fileno()
+                    err_codes = set()
+                    for err_name in ('EINVAL', 'ENOSYS', 'ENOTSUP', 'EBADF',
+                                     'ENOTSOCK', 'EOPNOTSUPP'):
+                        try:
+                            err_code = getattr(errno, err_name)
+                        except AttributeError:
+                            pass
+                        else:
+                            err_codes.add(err_code)
+                    try:
+                        while bcount > 0:
+                            bcount = os.sendfile(fdstno,
+                                                 fsrcno,
+                                                 offset,
+                                                 max_bcount)
+                            offset += bcount
+                    except OSError as e:
+                        if e.errno in err_codes:
+                            # sendfile is not supported or does not support
+                            # classic files (only sockets)
+                            pass
+                        else:
+                            raise
+                    else:
+                        # Copy with os.sendfile succeeded
+                        done = True
+                if not done:
+                    # sendfile is not available or failed, fallback
+                    # to copyfileobj
+                    copyfileobj(fsrc, fdst)
     return dst
 
 def copymode(src, dst, *, follow_symlinks=True):
diff -r 0e8743a6924e Lib/test/test_shutil.py
--- a/Lib/test/test_shutil.py	Sat Oct 31 12:23:03 2015 +0000
+++ b/Lib/test/test_shutil.py	Sat Oct 31 17:10:08 2015 +0100
@@ -606,6 +606,39 @@
         shutil.copyfile(link, dst)
         self.assertFalse(os.path.islink(dst))
 
+    @unittest.skipUnless(support.is_resource_enabled('largefile'),
+                         'test requires >4GB file support')
+    def test_copyfile_hugefile(self):
+        tmp_dir = self.mkdtemp()
+        src_path = os.path.join(tmp_dir, "src")
+        # Create a > 4GB file with non trivial content
+        chunk_size = 2 ** 14
+        with open(src_path, "wb") as src_file:
+            for offset in range(0, 2 ** 32 + chunk_size + 1, chunk_size):
+                # Generate and write a unique data chunk
+                chunk = str(offset).encode("ascii")
+                chunk = chunk + b"\x00" * (chunk_size - len(chunk))
+                src_file.write(chunk)
+        dst_path = os.path.join(tmp_dir, "dst")
+        try:
+            shutil.copyfile(src_path, dst_path)
+        except OSError as e:
+            if e.errno != getattr(errno, 'ENOSPC', -1):
+                raise
+            self.skipTest("not enough space left")
+        except OverflowError:
+            self.skipTest("no large file support, or not enough space left")
+        self.assertTrue(os.path.isfile(dst_path))
+        # Compare files
+        with open(src_path, "rb") as src_file, \
+                open(dst_path, "rb") as dst_file:
+            while True:
+                src_chunk = src_file.read(chunk_size)
+                dst_chunk = dst_file.read(chunk_size)
+                self.assertEqual(src_chunk, dst_chunk)
+                if not src_chunk:
+                    break
+
     def test_rmtree_uses_safe_fd_version_if_available(self):
         _use_fd_functions = ({os.open, os.stat, os.unlink, os.rmdir} <=
                              os.supports_dir_fd and