diff --git a/doc/api/fs.markdown b/doc/api/fs.markdown
index e535ce64e2..b46c94984f 100644
--- a/doc/api/fs.markdown
+++ b/doc/api/fs.markdown
@@ -468,9 +468,9 @@ The callback is given the three arguments, `(err, bytesRead, buffer)`.
 
 Synchronous version of `fs.read`. Returns the number of `bytesRead`.
 
-## fs.readFile(filename[, options], callback)
+## fs.readFile(file[, options], callback)
 
-* `filename` {String}
+* `file` {String | Integer} filename or file descriptor
 * `options` {Object | String}
   * `encoding` {String | Null} default = `null`
   * `flag` {String} default = `'r'`
@@ -492,18 +492,20 @@ If `options` is a string, then it specifies the encoding. Example:
 
     fs.readFile('/etc/passwd', 'utf8', callback);
 
+Any specified file descriptor has to support reading.
 
-## fs.readFileSync(filename[, options])
+_Note: Specified file descriptors will not be closed automatically._
 
-Synchronous version of `fs.readFile`. Returns the contents of the `filename`.
+## fs.readFileSync(file[, options])
+
+Synchronous version of `fs.readFile`. Returns the contents of the `file`.
 
 If the `encoding` option is specified then this function returns a
 string. Otherwise it returns a buffer.
 
+## fs.writeFile(file, data[, options], callback)
 
-## fs.writeFile(filename, data[, options], callback)
-
-* `filename` {String}
+* `file` {String | Integer} filename or file descriptor
 * `data` {String | Buffer}
 * `options` {Object | String}
   * `encoding` {String | Null} default = `'utf8'`
@@ -528,13 +530,21 @@ If `options` is a string, then it specifies the encoding. Example:
 
     fs.writeFile('message.txt', 'Hello Node.js', 'utf8', callback);
 
-## fs.writeFileSync(filename, data[, options])
+Any specified file descriptor has to support writing.
+
+Note that it is unsafe to use `fs.writeFile` multiple times on the same file
+without waiting for the callback. For this scenario,
+`fs.createWriteStream` is strongly recommended.
+
+_Note: Specified file descriptors will not be closed automatically._
+
+## fs.writeFileSync(file, data[, options])
 
 The synchronous version of `fs.writeFile`. Returns `undefined`.
 
-## fs.appendFile(filename, data[, options], callback)
+## fs.appendFile(file, data[, options], callback)
 
-* `filename` {String}
+* `file` {String | Integer} filename or file descriptor
 * `data` {String | Buffer}
 * `options` {Object | String}
   * `encoding` {String | Null} default = `'utf8'`
@@ -556,7 +566,11 @@ If `options` is a string, then it specifies the encoding. Example:
 
     fs.appendFile('message.txt', 'data to append', 'utf8', callback);
 
-## fs.appendFileSync(filename, data[, options])
+Any specified file descriptor has to have been opened for appending.
+
+_Note: Specified file descriptors will not be closed automatically._
+
+## fs.appendFileSync(file, data[, options])
 
 The synchronous version of `fs.appendFile`. Returns `undefined`.
 
diff --git a/lib/fs.js b/lib/fs.js
index fef4f7ba50..76873be14a 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -101,6 +101,10 @@ function nullCheck(path, callback) {
   return true;
 }
 
+function isFd(path) {
+  return (path >>> 0) === path;
+}
+
 // Static method to set the stats properties on a Stats object.
 fs.Stats = function(
     dev,
@@ -243,10 +247,18 @@ fs.readFile = function(path, options, callback_) {
     return;
 
   var context = new ReadFileContext(callback, encoding);
+  context.isUserFd = isFd(path); // file descriptor ownership
   var req = new FSReqWrap();
   req.context = context;
   req.oncomplete = readFileAfterOpen;
 
+  if (context.isUserFd) {
+    process.nextTick(function() {
+      req.oncomplete(null, path);
+    });
+    return;
+  }
+
   binding.open(pathModule._makeLong(path),
                stringToFlags(flag),
                0o666,
@@ -257,6 +269,7 @@ const kReadFileBufferLength = 8 * 1024;
 
 function ReadFileContext(callback, encoding) {
   this.fd = undefined;
+  this.isUserFd = undefined;
   this.size = undefined;
   this.callback = callback;
   this.buffers = null;
@@ -293,6 +306,14 @@ ReadFileContext.prototype.close = function(err) {
   req.oncomplete = readFileAfterClose;
   req.context = this;
   this.err = err;
+
+  if (this.isUserFd) {
+    process.nextTick(function() {
+      req.oncomplete(null);
+    });
+    return;
+  }
+
   binding.close(this.fd, req);
 };
 
@@ -394,7 +415,8 @@ fs.readFileSync = function(path, options) {
   assertEncoding(encoding);
 
   var flag = options.flag || 'r';
-  var fd = fs.openSync(path, flag, 0o666);
+  var isUserFd = isFd(path); // file descriptor ownership
+  var fd = isUserFd ? path : fs.openSync(path, flag, 0o666);
 
   var st;
   var size;
@@ -404,7 +426,7 @@ fs.readFileSync = function(path, options) {
     size = st.isFile() ? st.size : 0;
     threw = false;
   } finally {
-    if (threw) fs.closeSync(fd);
+    if (threw && !isUserFd) fs.closeSync(fd);
   }
 
   var pos = 0;
@@ -419,7 +441,7 @@ fs.readFileSync = function(path, options) {
       buffer = new Buffer(size);
       threw = false;
     } finally {
-      if (threw) fs.closeSync(fd);
+      if (threw && !isUserFd) fs.closeSync(fd);
     }
   }
 
@@ -442,14 +464,15 @@ fs.readFileSync = function(path, options) {
       }
       threw = false;
     } finally {
-      if (threw) fs.closeSync(fd);
+      if (threw && !isUserFd) fs.closeSync(fd);
     }
 
     pos += bytesRead;
     done = (bytesRead === 0) || (size !== 0 && pos >= size);
   }
 
-  fs.closeSync(fd);
+  if (!isUserFd)
+    fs.closeSync(fd);
 
   if (size === 0) {
     // data was collected into the buffers list.
@@ -1096,25 +1119,33 @@ fs.futimesSync = function(fd, atime, mtime) {
   binding.futimes(fd, atime, mtime);
 };
 
-function writeAll(fd, buffer, offset, length, position, callback_) {
+function writeAll(fd, isUserFd, buffer, offset, length, position, callback_) {
   var callback = maybeCallback(arguments[arguments.length - 1]);
 
   // write(fd, buffer, offset, length, position, callback)
   fs.write(fd, buffer, offset, length, position, function(writeErr, written) {
     if (writeErr) {
-      fs.close(fd, function() {
+      if (isUserFd) {
         if (callback) callback(writeErr);
-      });
+      } else {
+        fs.close(fd, function() {
+          if (callback) callback(writeErr);
+        });
+      }
     } else {
       if (written === length) {
-        fs.close(fd, callback);
+        if (isUserFd) {
+          if (callback) callback(null);
+        } else {
+          fs.close(fd, callback);
+        }
       } else {
         offset += written;
         length -= written;
         if (position !== null) {
           position += written;
         }
-        writeAll(fd, buffer, offset, length, position, callback);
+        writeAll(fd, isUserFd, buffer, offset, length, position, callback);
       }
     }
   });
@@ -1134,16 +1165,27 @@ fs.writeFile = function(path, data, options, callback_) {
   assertEncoding(options.encoding);
 
   var flag = options.flag || 'w';
+
+  if (isFd(path)) {
+    writeFd(path, true);
+    return;
+  }
+
   fs.open(path, flag, options.mode, function(openErr, fd) {
     if (openErr) {
       if (callback) callback(openErr);
     } else {
-      var buffer = (data instanceof Buffer) ? data : new Buffer('' + data,
-          options.encoding || 'utf8');
-      var position = /a/.test(flag) ? null : 0;
-      writeAll(fd, buffer, 0, buffer.length, position, callback);
+      writeFd(fd, false);
     }
   });
+
+  function writeFd(fd, isUserFd) {
+    var buffer = (data instanceof Buffer) ? data : new Buffer('' + data,
+        options.encoding || 'utf8');
+    var position = /a/.test(flag) ? null : 0;
+
+    writeAll(fd, isUserFd, buffer, 0, buffer.length, position, callback);
+  }
 };
 
 fs.writeFileSync = function(path, data, options) {
@@ -1158,7 +1200,9 @@ fs.writeFileSync = function(path, data, options) {
   assertEncoding(options.encoding);
 
   var flag = options.flag || 'w';
-  var fd = fs.openSync(path, flag, options.mode);
+  var isUserFd = isFd(path); // file descriptor ownership
+  var fd = isUserFd ? path : fs.openSync(path, flag, options.mode);
+
   if (!(data instanceof Buffer)) {
     data = new Buffer('' + data, options.encoding || 'utf8');
   }
@@ -1175,7 +1219,7 @@ fs.writeFileSync = function(path, data, options) {
       }
     }
   } finally {
-    fs.closeSync(fd);
+    if (!isUserFd) fs.closeSync(fd);
   }
 };
 
@@ -1192,6 +1236,11 @@ fs.appendFile = function(path, data, options, callback_) {
 
   if (!options.flag)
     options = util._extend({ flag: 'a' }, options);
+
+  // force append behavior when using a supplied file descriptor
+  if (isFd(path))
+    options.flag = 'a';
+
   fs.writeFile(path, data, options, callback);
 };
 
@@ -1203,9 +1252,14 @@ fs.appendFileSync = function(path, data, options) {
   } else if (typeof options !== 'object') {
     throwOptionsError(options);
   }
+
   if (!options.flag)
     options = util._extend({ flag: 'a' }, options);
 
+  // force append behavior when using a supplied file descriptor
+  if (isFd(path))
+    options.flag = 'a';
+
   fs.writeFileSync(path, data, options);
 };
 
diff --git a/test/parallel/test-fs-append-file-sync.js b/test/parallel/test-fs-append-file-sync.js
index 42e0790e1f..4c5ae870ec 100644
--- a/test/parallel/test-fs-append-file-sync.js
+++ b/test/parallel/test-fs-append-file-sync.js
@@ -66,6 +66,19 @@ var fileData4 = fs.readFileSync(filename4);
 assert.equal(Buffer.byteLength('' + num) + currentFileData.length,
              fileData4.length);
 
+// test that appendFile accepts file descriptors
+var filename5 = join(common.tmpDir, 'append-sync5.txt');
+fs.writeFileSync(filename5, currentFileData);
+
+var filename5fd = fs.openSync(filename5, 'a+', 0o600);
+fs.appendFileSync(filename5fd, data);
+fs.closeSync(filename5fd);
+
+var fileData5 = fs.readFileSync(filename5);
+
+assert.equal(Buffer.byteLength(data) + currentFileData.length,
+             fileData5.length);
+
 //exit logic for cleanup
 
 process.on('exit', function() {
@@ -73,4 +86,5 @@ process.on('exit', function() {
   fs.unlinkSync(filename2);
   fs.unlinkSync(filename3);
   fs.unlinkSync(filename4);
+  fs.unlinkSync(filename5);
 });
diff --git a/test/parallel/test-fs-append-file.js b/test/parallel/test-fs-append-file.js
index b20323bd14..01742aa6f8 100644
--- a/test/parallel/test-fs-append-file.js
+++ b/test/parallel/test-fs-append-file.js
@@ -92,11 +92,42 @@ fs.appendFile(filename4, n, { mode: m }, function(e) {
   });
 });
 
+// test that appendFile accepts file descriptors
+var filename5 = join(common.tmpDir, 'append5.txt');
+fs.writeFileSync(filename5, currentFileData);
+
+fs.open(filename5, 'a+', function(e, fd) {
+  if (e) throw e;
+
+  ncallbacks++;
+
+  fs.appendFile(fd, s, function(e) {
+    if (e) throw e;
+
+    ncallbacks++;
+
+    fs.close(fd, function(e) {
+      if (e) throw e;
+
+      ncallbacks++;
+
+      fs.readFile(filename5, function(e, buffer) {
+        if (e) throw e;
+
+        ncallbacks++;
+        assert.equal(Buffer.byteLength(s) + currentFileData.length,
+                     buffer.length);
+      });
+    });
+  });
+});
+
 process.on('exit', function() {
-  assert.equal(8, ncallbacks);
+  assert.equal(12, ncallbacks);
 
   fs.unlinkSync(filename);
   fs.unlinkSync(filename2);
   fs.unlinkSync(filename3);
   fs.unlinkSync(filename4);
+  fs.unlinkSync(filename5);
 });
diff --git a/test/parallel/test-fs-readfile-fd.js b/test/parallel/test-fs-readfile-fd.js
new file mode 100644
index 0000000000..fc63d480ab
--- /dev/null
+++ b/test/parallel/test-fs-readfile-fd.js
@@ -0,0 +1,47 @@
+'use strict';
+var common = require('../common');
+var assert = require('assert');
+
+var path = require('path'),
+    fs = require('fs'),
+    fn = path.join(common.fixturesDir, 'empty.txt');
+
+tempFd(function(fd, close) {
+  fs.readFile(fd, function(err, data) {
+    assert.ok(data);
+    close();
+  });
+});
+
+tempFd(function(fd, close) {
+  fs.readFile(fd, 'utf8', function(err, data) {
+    assert.strictEqual('', data);
+    close();
+  });
+});
+
+tempFdSync(function(fd) {
+  assert.ok(fs.readFileSync(fd));
+});
+
+tempFdSync(function(fd) {
+  assert.strictEqual('', fs.readFileSync(fd, 'utf8'));
+});
+
+function tempFd(callback) {
+  fs.open(fn, 'r', function(err, fd) {
+    if (err) throw err;
+
+    callback(fd, function() {
+      fs.close(fd, function(err) {
+        if (err) throw err;
+      });
+    });
+  });
+}
+
+function tempFdSync(callback) {
+  var fd = fs.openSync(fn, 'r');
+  callback(fd);
+  fs.closeSync(fd);
+}
diff --git a/test/parallel/test-fs-write-file-sync.js b/test/parallel/test-fs-write-file-sync.js
index 37373404da..72c0a2b19b 100644
--- a/test/parallel/test-fs-write-file-sync.js
+++ b/test/parallel/test-fs-write-file-sync.js
@@ -47,6 +47,18 @@ assert.equal('abc', content);
 
 assert.equal(mode, fs.statSync(file2).mode & mode);
 
+// Test writeFileSync with file descriptor
+var file3 = path.join(common.tmpDir, 'testWriteFileSyncFd.txt');
+
+var fd = fs.openSync(file3, 'w+', mode);
+fs.writeFileSync(fd, '123');
+fs.closeSync(fd);
+
+content = fs.readFileSync(file3, {encoding: 'utf8'});
+assert.equal('123', content);
+
+assert.equal(mode, fs.statSync(file3).mode & 0o777);
+
 // Verify that all opened files were closed.
 assert.equal(0, openCount);
 
diff --git a/test/parallel/test-fs-write-file.js b/test/parallel/test-fs-write-file.js
index 9ff3b3f39a..a29e841ea2 100644
--- a/test/parallel/test-fs-write-file.js
+++ b/test/parallel/test-fs-write-file.js
@@ -69,11 +69,40 @@ fs.writeFile(filename3, n, { mode: m }, function(e) {
   });
 });
 
+// test that writeFile accepts file descriptors
+var filename4 = join(common.tmpDir, 'test4.txt');
+var buf = new Buffer(s, 'utf8');
+
+fs.open(filename4, 'w+', function(e, fd) {
+  if (e) throw e;
+
+  ncallbacks++;
+
+  fs.writeFile(fd, s, function(e) {
+    if (e) throw e;
+
+    ncallbacks++;
+
+    fs.close(fd, function(e) {
+      if (e) throw e;
+
+      ncallbacks++;
+
+      fs.readFile(filename4, function(e, buffer) {
+        if (e) throw e;
+
+        ncallbacks++;
+        assert.equal(Buffer.byteLength(s), buffer.length);
+      });
+    });
+  });
+});
 
 process.on('exit', function() {
-  assert.equal(6, ncallbacks);
+  assert.equal(10, ncallbacks);
 
   fs.unlinkSync(filename);
   fs.unlinkSync(filename2);
   fs.unlinkSync(filename3);
+  fs.unlinkSync(filename4);
 });