diff --git a/demo/asset_section.js b/demo/asset_section.js
index 53c37a06b4..9aaad9e6a5 100644
--- a/demo/asset_section.js
+++ b/demo/asset_section.js
@@ -255,6 +255,16 @@ shakaDemo.preparePlayer_ = function(asset) {
   if (!isNaN(preferredAudioChannelCount)) {
     config.preferredAudioChannelCount = preferredAudioChannelCount;
   }
+  let availabilityWindowOverrideRaw =
+      document.getElementById('availabilityWindowOverride').value;
+  let availabilityWindowOverride = Number(availabilityWindowOverrideRaw);
+  if (!isNaN(availabilityWindowOverride) &&
+      availabilityWindowOverrideRaw.length) {
+    // Don't configure if the field contains an empty string; this is because
+    // Number('') evaluates to 0, which is a valid (if fairly useless) override
+    // value, while we would rather it mean "don't override".
+    config.manifest.availabilityWindowOverride = availabilityWindowOverride;
+  }
 
   config.abr.enabled =
       document.getElementById('enableAdaptation').checked;
diff --git a/demo/configuration_section.js b/demo/configuration_section.js
index c7ae1fbd02..b4e1874cfb 100644
--- a/demo/configuration_section.js
+++ b/demo/configuration_section.js
@@ -53,6 +53,8 @@ shakaDemo.setupConfiguration_ = function() {
       'input', shakaDemo.onDrmSettingsChange_);
   document.getElementById('drmSettingsAudioRobustness').addEventListener(
       'input', shakaDemo.onDrmSettingsChange_);
+  document.getElementById('availabilityWindowOverride').addEventListener(
+      'input', shakaDemo.onAvailabilityWindowOverrideChange_);
 
   let robustnessSuggestions = document.getElementById('robustnessSuggestions');
   if (shakaDemo.support_.drm['com.widevine.alpha']) {
@@ -86,6 +88,16 @@ shakaDemo.onDrmSettingsChange_ = function(event) {
 };
 
 
+/**
+ * @param {!Event} event
+ * @private
+ */
+shakaDemo.onAvailabilityWindowOverrideChange_ = function(event) {
+  // Change the hash, to mirror this.
+  shakaDemo.hashShouldChange_();
+};
+
+
 /**
  * @param {!Event} event
  * @private
diff --git a/demo/index.html b/demo/index.html
index d040c9e1d0..af87ae09e1 100644
--- a/demo/index.html
+++ b/demo/index.html
@@ -221,6 +221,10 @@ <h1>Shaka Player <span id="version"></span></h1>
           <label for="drmSettingsAudioRobustness">Audio Robustness:</label>
           <input id="drmSettingsAudioRobustness" type="text" class="flex-grow" list="robustnessSuggestions">
         </div>
+        <div>
+          <label for="availabilityWindowOverride">Availability Window Override:</label>
+          <input id="availabilityWindowOverride" type="number" step="30" min="0">
+        </div>
 	<datalist id="robustnessSuggestions"></datalist>
       </details>
 
diff --git a/demo/main.js b/demo/main.js
index afe799c148..970efca577 100644
--- a/demo/main.js
+++ b/demo/main.js
@@ -288,6 +288,10 @@ shakaDemo.preBrowserCheckParams_ = function(params) {
   if ('certificate' in params) {
     document.getElementById('certificateInput').value = params['certificate'];
   }
+  if ('availabilityWindowOverride' in params) {
+    document.getElementById('availabilityWindowOverride').value =
+        params['availabilityWindowOverride'];
+  }
   if ('logtoscreen' in params) {
     document.getElementById('logToScreen').checked = true;
     // Call onLogChange_ manually, because setting checked
@@ -581,6 +585,11 @@ shakaDemo.hashShouldChange_ = function() {
   if (document.getElementById('showNative').checked) {
     params.push('nativecontrols');
   }
+  let availabilityWindowOverride =
+      document.getElementById('availabilityWindowOverride').value;
+  if (availabilityWindowOverride) {
+    params.push('availabilityWindowOverride=' + availabilityWindowOverride);
+  }
   if (shaka.log) {
     let logLevelList = document.getElementById('logLevelList');
     let logLevel = logLevelList[logLevelList.selectedIndex].value;
diff --git a/externs/shaka/player.js b/externs/shaka/player.js
index eb43b6045b..b5cfde0054 100644
--- a/externs/shaka/player.js
+++ b/externs/shaka/player.js
@@ -529,11 +529,15 @@ shaka.extern.DashManifestConfiguration;
 /**
  * @typedef {{
  *   retryParameters: shaka.extern.RetryParameters,
+ *   availabilityWindowOverride: number,
  *   dash: shaka.extern.DashManifestConfiguration
  * }}
  *
  * @property {shaka.extern.RetryParameters} retryParameters
  *   Retry parameters for manifest requests.
+ * @property (number) availabilityWindowOverride
+ *   A number, in seconds, that overrides the availability window in the
+ *   manifest, or NaN if the default value should be used.
  * @property {shaka.extern.DashManifestConfiguration} dash
  *   Advanced parameters used by the DASH manifest parser.
  *
diff --git a/lib/player.js b/lib/player.js
index 10a73fee5b..0045319d2e 100644
--- a/lib/player.js
+++ b/lib/player.js
@@ -729,6 +729,11 @@ shaka.Player.prototype.load = async function(
 
     if (cancelValue) throw cancelValue;
 
+    if (!isNaN(this.config_.manifest.availabilityWindowOverride)) {
+      this.manifest_.presentationTimeline.setSegmentAvailabilityDuration(
+          this.config_.manifest.availabilityWindowOverride);
+    }
+
     this.filterManifestForAVVariants_();
 
     this.drmEngine_ = this.createDrmEngine();
@@ -2290,6 +2295,7 @@ shaka.Player.prototype.defaultConfig_ = function() {
     },
     manifest: {
       retryParameters: shaka.net.NetworkingEngine.defaultRetryParameters(),
+      availabilityWindowOverride: NaN,
       dash: {
         customScheme: function(node) {
           // Reference node to keep closure from removing it.
diff --git a/test/dash/dash_parser_content_protection_unit.js b/test/dash/dash_parser_content_protection_unit.js
index e4b0cad145..a567eac506 100644
--- a/test/dash/dash_parser_content_protection_unit.js
+++ b/test/dash/dash_parser_content_protection_unit.js
@@ -38,6 +38,7 @@ describe('DashParser ContentProtection', function() {
     callback = callback || function(node) { return null; };
     dashParser.configure({
       retryParameters: retry,
+      availabilityWindowOverride: NaN,
       dash: {
         clockSyncUri: '',
         customScheme: callback,
diff --git a/test/dash/dash_parser_live_unit.js b/test/dash/dash_parser_live_unit.js
index dfff7d9546..cf0271e41e 100644
--- a/test/dash/dash_parser_live_unit.js
+++ b/test/dash/dash_parser_live_unit.js
@@ -44,6 +44,7 @@ describe('DashParser Live', function() {
     parser = new shaka.dash.DashParser();
     parser.configure({
       retryParameters: retry,
+      availabilityWindowOverride: NaN,
       dash: {
         clockSyncUri: '',
         customScheme: function(node) { return null; },
diff --git a/test/hls/hls_live_unit.js b/test/hls/hls_live_unit.js
index b46501980b..c88251b5c3 100644
--- a/test/hls/hls_live_unit.js
+++ b/test/hls/hls_live_unit.js
@@ -120,6 +120,7 @@ describe('HlsParser live', function() {
     let retry = shaka.net.NetworkingEngine.defaultRetryParameters();
     config = {
       retryParameters: retry,
+      availabilityWindowOverride: NaN,
       dash: {
         customScheme: function(node) { return null; },
         clockSyncUri: '',
diff --git a/test/hls/hls_parser_unit.js b/test/hls/hls_parser_unit.js
index 85e1948521..d420ae608a 100644
--- a/test/hls/hls_parser_unit.js
+++ b/test/hls/hls_parser_unit.js
@@ -86,6 +86,7 @@ describe('HlsParser', function() {
     let retry = shaka.net.NetworkingEngine.defaultRetryParameters();
     config = {
       retryParameters: retry,
+      availabilityWindowOverride: NaN,
       dash: {
         customScheme: function(node) { return null; },
         clockSyncUri: '',
diff --git a/test/player_unit.js b/test/player_unit.js
index 95acebbf97..37da58feba 100644
--- a/test/player_unit.js
+++ b/test/player_unit.js
@@ -3135,6 +3135,45 @@ describe('Player', function() {
     });
   });
 
+  describe('live', function() {
+    function availabilityWindowTest(expectedAvailabilityWindow) {
+      // Create a live timeline and manifest.
+      let timeline = new shaka.media.PresentationTimeline(300, 0);
+      timeline.setStatic(false);
+      timeline.setSegmentAvailabilityDuration(100);
+
+      manifest = new shaka.test.ManifestGenerator()
+          .setTimeline(timeline)
+          .addPeriod(0)
+            .addVariant(0)
+            .addVideo(1)
+          .build();
+
+      let parser = new shaka.test.FakeManifestParser(manifest);
+      let parserFactory = function() { return parser; };
+
+      return player.load('', /* startTime */ 0, parserFactory).then(() => {
+        // Availability window can be determined by finding the time difference
+        // between the avalability end and start.  Thus, we can compare the
+        // expected and actual window.
+        let end = timeline.getSegmentAvailabilityEnd();
+        expect(end - timeline.getSegmentAvailabilityStart())
+            .toBeCloseTo(expectedAvailabilityWindow, 1);
+      });
+    }
+
+    it('uses normal availability window when not overridden', async () => {
+      // The availability start should be what was in the timeline (100).
+      await availabilityWindowTest(100);
+    });
+
+    it('honors availabilityWindowOverride', async () => {
+      player.configure({manifest: {availabilityWindowOverride: 200}});
+      // The availability start should be what was configured (200).
+      await availabilityWindowTest(200);
+    });
+  });
+
   describe('language methods', function() {
     let videoOnlyManifest;
     let parserFactory = function() {
diff --git a/test/test/util/dash_parser_util.js b/test/test/util/dash_parser_util.js
index 7de6e87108..6cd5850236 100644
--- a/test/test/util/dash_parser_util.js
+++ b/test/test/util/dash_parser_util.js
@@ -27,6 +27,7 @@ shaka.test.Dash.makeDashParser = function() {
   let parser = new shaka.dash.DashParser();
   parser.configure({
     retryParameters: retry,
+    availabilityWindowOverride: NaN,
     dash: {
       customScheme: function(node) { return null; },
       clockSyncUri: '',