diff --git a/externs/olx.js b/externs/olx.js
index 020241976b..bcfbb01c18 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -309,7 +309,8 @@ olx.MapOptions.prototype.view;
 
 /**
  * Object literal with config options for the overlay.
- * @typedef {{element: (Element|undefined),
+ * @typedef {{id: (number|string|undefined),
+ *     element: (Element|undefined),
  *     offset: (Array.<number>|undefined),
  *     position: (ol.Coordinate|undefined),
  *     positioning: (ol.OverlayPositioning|string|undefined),
@@ -323,6 +324,15 @@ olx.MapOptions.prototype.view;
 olx.OverlayOptions;
 
 
+/**
+ * Set the overlay id. The overlay id can be used with the
+ * {@link ol.Map#getOverlayById} method.
+ * @type {number|string|undefined}
+ * @api
+ */
+olx.OverlayOptions.prototype.id;
+
+
 /**
  * The overlay element.
  * @type {Element|undefined}
diff --git a/src/ol/map.js b/src/ol/map.js
index c9f92062cb..15fda71a25 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -342,6 +342,13 @@ ol.Map = function(options) {
    */
   this.overlays_ = optionsInternal.overlays;
 
+  /**
+   * A lookup of overlays by id.
+   * @private
+   * @type {Object.<string, ol.Overlay>}
+   */
+  this.overlayIdIndex_ = {};
+
   /**
    * @type {ol.renderer.Map}
    * @private
@@ -460,21 +467,14 @@ ol.Map = function(options) {
         event.element.setMap(null);
       }, false, this);
 
-  this.overlays_.forEach(
-      /**
-       * @param {ol.Overlay} overlay Overlay.
-       * @this {ol.Map}
-       */
-      function(overlay) {
-        overlay.setMap(this);
-      }, this);
+  this.overlays_.forEach(this.addOverlayInternal_, this);
 
   goog.events.listen(this.overlays_, ol.CollectionEventType.ADD,
       /**
        * @param {ol.CollectionEvent} event Collection event.
        */
       function(event) {
-        event.element.setMap(this);
+        this.addOverlayInternal_(/** @type {ol.Overlay} */ (event.element));
       }, false, this);
 
   goog.events.listen(this.overlays_, ol.CollectionEventType.REMOVE,
@@ -482,6 +482,10 @@ ol.Map = function(options) {
        * @param {ol.CollectionEvent} event Collection event.
        */
       function(event) {
+        var id = event.element.getId();
+        if (id !== undefined) {
+          delete this.overlayIdIndex_[id.toString()];
+        }
         event.element.setMap(null);
       }, false, this);
 
@@ -539,6 +543,20 @@ ol.Map.prototype.addOverlay = function(overlay) {
 };
 
 
+/**
+ * This deals with map's overlay collection changes.
+ * @param {ol.Overlay} overlay Overlay.
+ * @private
+ */
+ol.Map.prototype.addOverlayInternal_ = function(overlay) {
+  var id = overlay.getId();
+  if (id !== undefined) {
+    this.overlayIdIndex_[id.toString()] = overlay;
+  }
+  overlay.setMap(this);
+};
+
+
 /**
  * Add functions to be called before rendering. This can be used for attaching
  * animations before updating the map's view.  The {@link ol.animation}
@@ -767,6 +785,20 @@ ol.Map.prototype.getOverlays = function() {
 };
 
 
+/**
+ * Get an overlay by its identifier (the value returned by overlay.getId()).
+ * Note that the index treats string and numeric identifiers as the same. So
+ * `map.getOverlayById(2)` will return an overlay with id `'2'` or `2`.
+ * @param {string|number} id Overlay identifier.
+ * @return {ol.Overlay} Overlay.
+ * @api
+ */
+ol.Map.prototype.getOverlayById = function(id) {
+  var overlay = this.overlayIdIndex_[id.toString()];
+  return overlay !== undefined ? overlay : null;
+};
+
+
 /**
  * Get the map interactions. Modifying this collection changes the interactions
  * associated with the map.
diff --git a/src/ol/overlay.js b/src/ol/overlay.js
index 9580560d96..6abd39d9a7 100644
--- a/src/ol/overlay.js
+++ b/src/ol/overlay.js
@@ -73,6 +73,12 @@ ol.Overlay = function(options) {
 
   goog.base(this);
 
+  /**
+   * @private
+   * @type {number|string|undefined}
+   */
+  this.id_ = options.id;
+
   /**
    * @private
    * @type {boolean}
@@ -187,6 +193,16 @@ ol.Overlay.prototype.getElement = function() {
 };
 
 
+/**
+ * Get the overlay identifier which is set on constructor.
+ * @return {number|string|undefined} Id.
+ * @api
+ */
+ol.Overlay.prototype.getId = function() {
+  return this.id_;
+};
+
+
 /**
  * Get the map associated with this overlay.
  * @return {ol.Map|undefined} The map that the overlay is part of.
diff --git a/test/spec/ol/map.test.js b/test/spec/ol/map.test.js
index 85f58ddd36..78ca851136 100644
--- a/test/spec/ol/map.test.js
+++ b/test/spec/ol/map.test.js
@@ -315,6 +315,69 @@ describe('ol.Map', function() {
       });
     });
 
+    describe('#getOverlayById()', function() {
+      var target, map, overlay, overlay_target;
+
+      beforeEach(function() {
+        target = document.createElement('div');
+        var style = target.style;
+        style.position = 'absolute';
+        style.left = '-1000px';
+        style.top = '-1000px';
+        style.width = '360px';
+        style.height = '180px';
+        document.body.appendChild(target);
+        map = new ol.Map({
+          target: target,
+          view: new ol.View({
+            projection: 'EPSG:4326',
+            center: [0, 0],
+            resolution: 1
+          })
+        });
+        overlay_target = document.createElement('div');
+      });
+
+      afterEach(function() {
+        map.removeOverlay(overlay);
+        goog.dispose(map);
+        document.body.removeChild(target);
+      });
+
+      it('returns an overlay by id', function() {
+        overlay = new ol.Overlay({
+          id: 'foo',
+          element: overlay_target,
+          position: [0, 0]
+        });
+        map.addOverlay(overlay);
+        expect(map.getOverlayById('foo')).to.be(overlay);
+      });
+
+      it('returns null when no overlay is found', function() {
+        overlay = new ol.Overlay({
+          id: 'foo',
+          element: overlay_target,
+          position: [0, 0]
+        });
+        map.addOverlay(overlay);
+        expect(map.getOverlayById('bar')).to.be(null);
+      });
+
+      it('returns null after removing overlay', function() {
+        overlay = new ol.Overlay({
+          id: 'foo',
+          element: overlay_target,
+          position: [0, 0]
+        });
+        map.addOverlay(overlay);
+        expect(map.getOverlayById('foo')).to.be(overlay);
+        map.removeOverlay(overlay);
+        expect(map.getOverlayById('foo')).to.be(null);
+      });
+
+    });
+
   });
 
 });
@@ -325,6 +388,7 @@ goog.require('goog.events.BrowserEvent');
 goog.require('goog.events.EventType');
 goog.require('ol.Map');
 goog.require('ol.MapEvent');
+goog.require('ol.Overlay');
 goog.require('ol.View');
 goog.require('ol.interaction');
 goog.require('ol.interaction.Interaction');
diff --git a/test/spec/ol/overlay.test.js b/test/spec/ol/overlay.test.js
index 3f1f1e3790..468e58d1da 100644
--- a/test/spec/ol/overlay.test.js
+++ b/test/spec/ol/overlay.test.js
@@ -1,6 +1,36 @@
 goog.provide('ol.test.Overlay');
 
 describe('ol.Overlay', function() {
+  var target, map;
+
+  var width = 360;
+  var height = 180;
+
+  beforeEach(function() {
+    target = document.createElement('div');
+
+    var style = target.style;
+    style.position = 'absolute';
+    style.left = '-1000px';
+    style.top = '-1000px';
+    style.width = width + 'px';
+    style.height = height + 'px';
+    document.body.appendChild(target);
+
+    map = new ol.Map({
+      target: target,
+      view: new ol.View({
+        projection: 'EPSG:4326',
+        center: [0, 0],
+        resolution: 1
+      })
+    });
+  });
+
+  afterEach(function() {
+    goog.dispose(map);
+    document.body.removeChild(target);
+  });
 
   describe('constructor', function() {
 
@@ -11,6 +41,38 @@ describe('ol.Overlay', function() {
 
   });
 
+  describe('#getId()', function() {
+    var overlay, target;
+
+    beforeEach(function() {
+      target = document.createElement('div');
+    });
+    afterEach(function() {
+      map.removeOverlay(overlay);
+    });
+
+    it('returns the overlay identifier', function() {
+      overlay = new ol.Overlay({
+        element: target,
+        position: [0, 0]
+      });
+      map.addOverlay(overlay);
+      expect(overlay.getId()).to.be(undefined);
+      map.removeOverlay(overlay);
+      overlay = new ol.Overlay({
+        id: 'foo',
+        element: target,
+        position: [0, 0]
+      });
+      map.addOverlay(overlay);
+      expect(overlay.getId()).to.be('foo');
+    });
+
+  });
+
 });
 
+goog.require('goog.dispose');
+goog.require('ol.Map');
 goog.require('ol.Overlay');
+goog.require('ol.View');