diff --git a/CHANGELOG b/CHANGELOG
index b0f6a0314d9..4bb4db4c47b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -50,6 +50,7 @@ v 8.4.0 (unreleased)
   - Fix Encoding::CompatibilityError bug when markdown content has some complex URL (Jason Lee)
   - Add API support for managing build variables of project
   - Allow broadcast messages to be edited
+  - Autosize Markdown textareas
 
 v 8.3.4
   - Use gitlab-workhorse 0.5.4 (fixes API routing bug)
diff --git a/app/assets/javascripts/behaviors/autosize.js.coffee b/app/assets/javascripts/behaviors/autosize.js.coffee
new file mode 100644
index 00000000000..b32072e61ee
--- /dev/null
+++ b/app/assets/javascripts/behaviors/autosize.js.coffee
@@ -0,0 +1,4 @@
+#= require autosize
+
+$ ->
+  autosize($('.js-autosize'))
diff --git a/app/assets/javascripts/notes.js.coffee b/app/assets/javascripts/notes.js.coffee
index fcf50dd1b51..356fb6aa08c 100644
--- a/app/assets/javascripts/notes.js.coffee
+++ b/app/assets/javascripts/notes.js.coffee
@@ -1,4 +1,5 @@
 #= require autosave
+#= require autosize
 #= require dropzone
 #= require dropzone_input
 #= require gfm_auto_complete
@@ -246,6 +247,7 @@ class @Notes
       else
         previewButton.removeClass("turn-on").addClass "turn-off"
 
+    autosize(textarea)
     new Autosave textarea, [
       "Note"
       form.find("#note_commit_id").val()
diff --git a/app/assets/stylesheets/framework/markdown_area.scss b/app/assets/stylesheets/framework/markdown_area.scss
index c540e527bed..6732343802a 100644
--- a/app/assets/stylesheets/framework/markdown_area.scss
+++ b/app/assets/stylesheets/framework/markdown_area.scss
@@ -83,6 +83,7 @@
   background: #FFF;
   border: 1px solid #ddd;
   min-height: 140px;
+  max-height: 430px;
   padding: 5px;
   box-shadow: none;
   width: 100%;
diff --git a/app/assets/stylesheets/pages/note_form.scss b/app/assets/stylesheets/pages/note_form.scss
index d86259f93fb..2c9a42f9892 100644
--- a/app/assets/stylesheets/pages/note_form.scss
+++ b/app/assets/stylesheets/pages/note_form.scss
@@ -159,6 +159,7 @@
 .edit_note {
   .markdown-area {
     min-height: 140px;
+    max-height: 430px;
   }
   .note-form-actions {
     background: transparent;
diff --git a/app/views/projects/_zen.html.haml b/app/views/projects/_zen.html.haml
index d5829568275..e701253d7de 100644
--- a/app/views/projects/_zen.html.haml
+++ b/app/views/projects/_zen.html.haml
@@ -1,6 +1,6 @@
 .zennable
   .zen-backdrop
-    - classes << ' js-gfm-input markdown-area'
+    - classes << ' js-gfm-input js-autosize markdown-area'
     - if defined?(f) && f
       = f.text_area attr, class: classes
     - else
diff --git a/vendor/assets/javascripts/autosize.js b/vendor/assets/javascripts/autosize.js
new file mode 100755
index 00000000000..cfa49e72c50
--- /dev/null
+++ b/vendor/assets/javascripts/autosize.js
@@ -0,0 +1,243 @@
+/*!
+	Autosize 3.0.14
+	license: MIT
+	http://www.jacklmoore.com/autosize
+*/
+(function (global, factory) {
+	if (typeof define === 'function' && define.amd) {
+		define(['exports', 'module'], factory);
+	} else if (typeof exports !== 'undefined' && typeof module !== 'undefined') {
+		factory(exports, module);
+	} else {
+		var mod = {
+			exports: {}
+		};
+		factory(mod.exports, mod);
+		global.autosize = mod.exports;
+	}
+})(this, function (exports, module) {
+	'use strict';
+
+	var set = typeof Set === 'function' ? new Set() : (function () {
+		var list = [];
+
+		return {
+			has: function has(key) {
+				return Boolean(list.indexOf(key) > -1);
+			},
+			add: function add(key) {
+				list.push(key);
+			},
+			'delete': function _delete(key) {
+				list.splice(list.indexOf(key), 1);
+			} };
+	})();
+
+	function assign(ta) {
+		var _ref = arguments[1] === undefined ? {} : arguments[1];
+
+		var _ref$setOverflowX = _ref.setOverflowX;
+		var setOverflowX = _ref$setOverflowX === undefined ? true : _ref$setOverflowX;
+		var _ref$setOverflowY = _ref.setOverflowY;
+		var setOverflowY = _ref$setOverflowY === undefined ? true : _ref$setOverflowY;
+
+		if (!ta || !ta.nodeName || ta.nodeName !== 'TEXTAREA' || set.has(ta)) return;
+
+		var heightOffset = null;
+		var overflowY = null;
+		var clientWidth = ta.clientWidth;
+
+		function init() {
+			var style = window.getComputedStyle(ta, null);
+
+			overflowY = style.overflowY;
+
+			if (style.resize === 'vertical') {
+				ta.style.resize = 'none';
+			} else if (style.resize === 'both') {
+				ta.style.resize = 'horizontal';
+			}
+
+			if (style.boxSizing === 'content-box') {
+				heightOffset = -(parseFloat(style.paddingTop) + parseFloat(style.paddingBottom));
+			} else {
+				heightOffset = parseFloat(style.borderTopWidth) + parseFloat(style.borderBottomWidth);
+			}
+			// Fix when a textarea is not on document body and heightOffset is Not a Number
+			if (isNaN(heightOffset)) {
+				heightOffset = 0;
+			}
+
+			update();
+		}
+
+		function changeOverflow(value) {
+			{
+				// Chrome/Safari-specific fix:
+				// When the textarea y-overflow is hidden, Chrome/Safari do not reflow the text to account for the space
+				// made available by removing the scrollbar. The following forces the necessary text reflow.
+				var width = ta.style.width;
+				ta.style.width = '0px';
+				// Force reflow:
+				/* jshint ignore:start */
+				ta.offsetWidth;
+				/* jshint ignore:end */
+				ta.style.width = width;
+			}
+
+			overflowY = value;
+
+			if (setOverflowY) {
+				ta.style.overflowY = value;
+			}
+
+			resize();
+		}
+
+		function resize() {
+			var htmlTop = window.pageYOffset;
+			var bodyTop = document.body.scrollTop;
+			var originalHeight = ta.style.height;
+
+			ta.style.height = 'auto';
+
+			var endHeight = ta.scrollHeight + heightOffset;
+
+			if (ta.scrollHeight === 0) {
+				// If the scrollHeight is 0, then the element probably has display:none or is detached from the DOM.
+				ta.style.height = originalHeight;
+				return;
+			}
+
+			ta.style.height = endHeight + 'px';
+
+			// used to check if an update is actually necessary on window.resize
+			clientWidth = ta.clientWidth;
+
+			// prevents scroll-position jumping
+			document.documentElement.scrollTop = htmlTop;
+			document.body.scrollTop = bodyTop;
+		}
+
+		function update() {
+			var startHeight = ta.style.height;
+
+			resize();
+
+			var style = window.getComputedStyle(ta, null);
+
+			if (style.height !== ta.style.height) {
+				if (overflowY !== 'visible') {
+					changeOverflow('visible');
+				}
+			} else {
+				if (overflowY !== 'hidden') {
+					changeOverflow('hidden');
+				}
+			}
+
+			if (startHeight !== ta.style.height) {
+				var evt = document.createEvent('Event');
+				evt.initEvent('autosize:resized', true, false);
+				ta.dispatchEvent(evt);
+			}
+		}
+
+		var pageResize = function pageResize() {
+			if (ta.clientWidth !== clientWidth) {
+				update();
+			}
+		};
+
+		var destroy = (function (style) {
+			window.removeEventListener('resize', pageResize, false);
+			ta.removeEventListener('input', update, false);
+			ta.removeEventListener('keyup', update, false);
+			ta.removeEventListener('autosize:destroy', destroy, false);
+			ta.removeEventListener('autosize:update', update, false);
+			set['delete'](ta);
+
+			Object.keys(style).forEach(function (key) {
+				ta.style[key] = style[key];
+			});
+		}).bind(ta, {
+			height: ta.style.height,
+			resize: ta.style.resize,
+			overflowY: ta.style.overflowY,
+			overflowX: ta.style.overflowX,
+			wordWrap: ta.style.wordWrap });
+
+		ta.addEventListener('autosize:destroy', destroy, false);
+
+		// IE9 does not fire onpropertychange or oninput for deletions,
+		// so binding to onkeyup to catch most of those events.
+		// There is no way that I know of to detect something like 'cut' in IE9.
+		if ('onpropertychange' in ta && 'oninput' in ta) {
+			ta.addEventListener('keyup', update, false);
+		}
+
+		window.addEventListener('resize', pageResize, false);
+		ta.addEventListener('input', update, false);
+		ta.addEventListener('autosize:update', update, false);
+		set.add(ta);
+
+		if (setOverflowX) {
+			ta.style.overflowX = 'hidden';
+			ta.style.wordWrap = 'break-word';
+		}
+
+		init();
+	}
+
+	function destroy(ta) {
+		if (!(ta && ta.nodeName && ta.nodeName === 'TEXTAREA')) return;
+		var evt = document.createEvent('Event');
+		evt.initEvent('autosize:destroy', true, false);
+		ta.dispatchEvent(evt);
+	}
+
+	function update(ta) {
+		if (!(ta && ta.nodeName && ta.nodeName === 'TEXTAREA')) return;
+		var evt = document.createEvent('Event');
+		evt.initEvent('autosize:update', true, false);
+		ta.dispatchEvent(evt);
+	}
+
+	var autosize = null;
+
+	// Do nothing in Node.js environment and IE8 (or lower)
+	if (typeof window === 'undefined' || typeof window.getComputedStyle !== 'function') {
+		autosize = function (el) {
+			return el;
+		};
+		autosize.destroy = function (el) {
+			return el;
+		};
+		autosize.update = function (el) {
+			return el;
+		};
+	} else {
+		autosize = function (el, options) {
+			if (el) {
+				Array.prototype.forEach.call(el.length ? el : [el], function (x) {
+					return assign(x, options);
+				});
+			}
+			return el;
+		};
+		autosize.destroy = function (el) {
+			if (el) {
+				Array.prototype.forEach.call(el.length ? el : [el], destroy);
+			}
+			return el;
+		};
+		autosize.update = function (el) {
+			if (el) {
+				Array.prototype.forEach.call(el.length ? el : [el], update);
+			}
+			return el;
+		};
+	}
+
+	module.exports = autosize;
+});
\ No newline at end of file