diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -780,7 +780,7 @@
    :meth:`__index__` method that returns an integer.
 
 
-.. function:: open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True)
+.. function:: open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, dirfd=-1)
 
    Open *file* and return a corresponding stream.  If the file cannot be opened,
    an :exc:`IOError` is raised.
@@ -887,6 +887,11 @@
    closed.  If a filename is given *closefd* has no effect and must be ``True``
    (the default).
 
+   If an open file descriptor to a directory is given as *dirfd*, *name* will be
+   opened relative to that directory. This requires that the operating system
+   supports the :c:func:`openat` system call (otherwise it raises
+   :exc:`NotImplementedError`).
+
    The type of file object returned by the :func:`open` function depends on the
    mode.  When :func:`open` is used to open a file in a text mode (``'w'``,
    ``'r'``, ``'wt'``, ``'rt'``, etc.), it returns a subclass of
diff --git a/Doc/library/io.rst b/Doc/library/io.rst
--- a/Doc/library/io.rst
+++ b/Doc/library/io.rst
@@ -462,7 +462,7 @@
 Raw File I/O
 ^^^^^^^^^^^^
 
-.. class:: FileIO(name, mode='r', closefd=True)
+.. class:: FileIO(name, mode='r', closefd=True, dirfd=-1)
 
    :class:`FileIO` represents an OS-level file containing bytes data.
    It implements the :class:`RawIOBase` interface (and therefore the
@@ -483,6 +483,11 @@
    The :meth:`read` (when called with a positive argument), :meth:`readinto`
    and :meth:`write` methods on this class will only make one system call.
 
+   If an open file descriptor to a directory is given as *dirfd*, *name* will be
+   opened relative to that directory. This requires that the operating system
+   supports the :c:func:`openat` system call (otherwise it raises
+   :exc:`NotImplementedError`).
+
    In addition to the attributes and methods from :class:`IOBase` and
    :class:`RawIOBase`, :class:`FileIO` provides the following data
    attributes and methods:
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -36,7 +36,7 @@
 
 
 def open(file, mode="r", buffering=-1, encoding=None, errors=None,
-         newline=None, closefd=True):
+         newline=None, closefd=True, dirfd=-1):
 
     r"""Open file and return a stream.  Raise IOError upon failure.
 
@@ -131,6 +131,10 @@
     be kept open when the file is closed. This does not work when a file name is
     given and must be True in that case.
 
+    If dirfd is specified, the file is opened relative to the given file
+    descriptor opened at a directory.  This requires underlying support from
+    the operating system.
+
     open() returns a file object whose type depends on the mode, and
     through which the standard file operations such as reading and writing
     are performed. When open() is used to open a file in a text mode ('w',
@@ -185,7 +189,7 @@
                  (writing and "w" or "") +
                  (appending and "a" or "") +
                  (updating and "+" or ""),
-                 closefd)
+                 closefd, dirfd)
     line_buffering = False
     if buffering == 1 or buffering < 0 and raw.isatty():
         buffering = -1
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -553,6 +553,15 @@
             file = self.open(f.fileno(), "r", closefd=False)
             self.assertEqual(file.buffer.raw.closefd, False)
 
+    @unittest.skipUnless(hasattr(os, 'openat'), "test needs os.openat()")
+    def test_dirfd(self):
+        with self.open(support.TESTFN, "w") as f:
+            f.write("egg\n")
+        dfd = os.open(os.getcwd(), os.O_RDONLY)
+        self.addCleanup(os.close, dfd)
+        with self.open(support.TESTFN, "r", dirfd=dfd) as f:
+            self.assertEqual(f.read(), "egg\n")
+
     def test_garbage_collection(self):
         # FileIO objects are collected, and collecting them flushes
         # all data to disk.
diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
--- a/Modules/_io/_iomodule.c
+++ b/Modules/_io/_iomodule.c
@@ -293,10 +293,10 @@
 {
     char *kwlist[] = {"file", "mode", "buffering",
                       "encoding", "errors", "newline",
-                      "closefd", NULL};
+                      "closefd", "dirfd", NULL};
     PyObject *file;
     char *mode = "r";
-    int buffering = -1, closefd = 1;
+    int buffering = -1, closefd = 1, dirfd = -1;
     char *encoding = NULL, *errors = NULL, *newline = NULL;
     unsigned i;
 
@@ -308,10 +308,10 @@
 
     PyObject *raw, *modeobj = NULL, *buffer = NULL, *wrapper = NULL;
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|sizzzi:open", kwlist,
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|sizzzii:open", kwlist,
                                      &file, &mode, &buffering,
                                      &encoding, &errors, &newline,
-                                     &closefd)) {
+                                     &closefd, &dirfd)) {
         return NULL;
     }
 
@@ -411,7 +411,7 @@
 
     /* Create the Raw file stream */
     raw = PyObject_CallFunction((PyObject *)&PyFileIO_Type,
-				"Osi", file, rawmode, closefd);
+				"Osii", file, rawmode, closefd, dirfd);
     if (raw == NULL)
         return NULL;
 
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -217,7 +217,7 @@
 fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
 {
     fileio *self = (fileio *) oself;
-    static char *kwlist[] = {"file", "mode", "closefd", NULL};
+    static char *kwlist[] = {"file", "mode", "closefd", "dirfd", NULL};
     const char *name = NULL;
     PyObject *nameobj, *stringobj = NULL;
     char *mode = "r";
@@ -230,6 +230,7 @@
     int flags = 0;
     int fd = -1;
     int closefd = 1;
+    int dirfd = -1;
 
     assert(PyFileIO_Check(oself));
     if (self->fd >= 0) {
@@ -238,10 +239,18 @@
             return -1;
     }
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|si:fileio",
-                                     kwlist, &nameobj, &mode, &closefd))
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|sii:fileio",
+                                     kwlist, &nameobj, &mode, &closefd, &dirfd))
         return -1;
 
+#ifndef HAVE_OPENAT
+    if (dirfd != -1) {
+        PyErr_SetString(PyExc_NotImplementedError,
+                        "using dirfd requires openat()");
+        return -1;
+    }
+#endif
+
     if (PyFloat_Check(nameobj)) {
         PyErr_SetString(PyExc_TypeError,
                         "integer argument expected, got float");
@@ -373,7 +382,16 @@
             self->fd = _wopen(widename, flags, 0666);
         else
 #endif
-            self->fd = open(name, flags, 0666);
+#ifdef HAVE_OPENAT
+        {
+            if (dirfd == -1)
+                self->fd = open(name, flags, 0666);
+            else
+                self->fd = openat(dirfd, name, flags, 0666);
+        }
+#else
+        self->fd = open(name, flags, 0666);
+#endif
         Py_END_ALLOW_THREADS
         if (self->fd < 0) {
 #ifdef MS_WINDOWS
@@ -1021,13 +1039,15 @@
 
 
 PyDoc_STRVAR(fileio_doc,
-"file(name: str[, mode: str]) -> file IO object\n"
+"file(name: str[, mode: str][, dirfd: int]) -> file IO object\n"
 "\n"
 "Open a file.  The mode can be 'r', 'w' or 'a' for reading (default),\n"
 "writing or appending.  The file will be created if it doesn't exist\n"
 "when opened for writing or appending; it will be truncated when\n"
 "opened for writing.  Add a '+' to the mode to allow simultaneous\n"
-"reading and writing.");
+"reading and writing.  If dirfd is specified, the file is opened relative\n"
+"to the given file descriptor opened at a directory.  This requires\n"
+"underlying support from the operating system.");
 
 PyDoc_STRVAR(read_doc,
 "read(size: int) -> bytes.  read at most size bytes, returned as bytes.\n"