diff --git a/externs/shaka/player.js b/externs/shaka/player.js
index 0be58f147a..a0ea3f28ac 100644
--- a/externs/shaka/player.js
+++ b/externs/shaka/player.js
@@ -574,7 +574,8 @@ shaka.extern.AdvancedDrmConfiguration;
  *       ((function(!Uint8Array, string, ?shaka.extern.DrmInfo):!Uint8Array)|
  *         undefined),
  *   logLicenseExchange: boolean,
- *   updateExpirationTime: number
+ *   updateExpirationTime: number,
+ *   preferredKeySystems: !Array.<string>
  * }}
  *
  * @property {shaka.extern.RetryParameters} retryParameters
@@ -612,6 +613,9 @@ shaka.extern.AdvancedDrmConfiguration;
  * @property {number} updateExpirationTime
  *   <i>Defaults to 1.</i> <br>
  *   The frequency in seconds with which to check the expiration of a session.
+ * @property {!Array.<string>} preferredKeySystems
+ *   <i>Defaults to an empty array. </i> <br>
+ *   Specifies the priorties of available DRM key systems.
  *
  * @exportDoc
  */
diff --git a/lib/media/drm_engine.js b/lib/media/drm_engine.js
index 7f3424f708..e34314749b 100644
--- a/lib/media/drm_engine.js
+++ b/lib/media/drm_engine.js
@@ -1016,6 +1016,22 @@ shaka.media.DrmEngine = class {
           shaka.util.Error.Category.DRM,
           shaka.util.Error.Code.NO_RECOGNIZED_KEY_SYSTEMS);
     }
+
+    // If we have configured preferredKeySystems, choose a preferred keySystem
+    // if available.
+    for (const preferredKeySystem of this.config_.preferredKeySystems) {
+      for (const variant of variants) {
+        const decodingInfo = variant.decodingInfos.find((decodingInfo) => {
+          return decodingInfo.supported &&
+              decodingInfo.keySystemAccess != null &&
+              decodingInfo.keySystemAccess.keySystem == preferredKeySystem;
+        });
+        if (decodingInfo) {
+          return decodingInfo.keySystemAccess;
+        }
+      }
+    }
+
     // Try key systems with configured license servers first.  We only have to
     // try key systems without configured license servers for diagnostic
     // reasons, so that we can differentiate between "none of these key
@@ -1071,6 +1087,24 @@ shaka.media.DrmEngine = class {
       }
     }
 
+    // If we have configured preferredKeySystems, choose the preferred one if
+    // available.
+    for (const keySystem of this.config_.preferredKeySystems) {
+      if (configsByKeySystem.has(keySystem)) {
+        const config = configsByKeySystem.get(keySystem);
+        try {
+          mediaKeySystemAccess =  // eslint-disable-next-line no-await-in-loop
+              await navigator.requestMediaKeySystemAccess(keySystem, [config]);
+          return mediaKeySystemAccess;
+        } catch (error) {
+          // Suppress errors.
+          shaka.log.v2(
+              'Requesting', keySystem, 'failed with config', config, error);
+        }
+        this.destroyer_.ensureNotDestroyed();
+      }
+    }
+
     // Try key systems with configured license servers first.  We only have to
     // try key systems without configured license servers for diagnostic
     // reasons, so that we can differentiate between "none of these key
@@ -1092,14 +1126,13 @@ shaka.media.DrmEngine = class {
 
         try {
           mediaKeySystemAccess =  // eslint-disable-next-line no-await-in-loop
-              await navigator.requestMediaKeySystemAccess(
-                  keySystem, [config]);
+              await navigator.requestMediaKeySystemAccess(keySystem, [config]);
           return mediaKeySystemAccess;
         } catch (error) {
+          // Suppress errors.
           shaka.log.v2(
-              'Requesting', keySystem, 'failed with config',
-              config, error);
-        } // Suppress errors.
+              'Requesting', keySystem, 'failed with config', config, error);
+        }
         this.destroyer_.ensureNotDestroyed();
       }
     }
diff --git a/lib/util/player_configuration.js b/lib/util/player_configuration.js
index 5cd3ebad2e..03fe4e2c54 100644
--- a/lib/util/player_configuration.js
+++ b/lib/util/player_configuration.js
@@ -75,6 +75,7 @@ shaka.util.PlayerConfiguration = class {
       initDataTransform: shaka.media.DrmEngine.defaultInitDataTransform,
       logLicenseExchange: false,
       updateExpirationTime: 1,
+      preferredKeySystems: [],
     };
 
     const manifest = {
diff --git a/test/media/drm_engine_unit.js b/test/media/drm_engine_unit.js
index 8b276d450d..a4dbc65217 100644
--- a/test/media/drm_engine_unit.js
+++ b/test/media/drm_engine_unit.js
@@ -257,6 +257,30 @@ function testDrmEngine(useMediaCapabilities) {
       }
     });
 
+    it('chooses systems by configured preferredKeySystems', async () => {
+      // Accept both drm.abc and drm.def.  Only one can be chosen.
+      setRequestMediaKeySystemAccessSpy(['drm.abc', 'drm.def']);
+      config.preferredKeySystems = ['drm.def'];
+      drmEngine.configure(config);
+      logErrorSpy.and.stub();
+
+      const variants = manifest.variants;
+      await drmEngine.initForPlayback(variants, manifest.offlineSessionIds,
+          useMediaCapabilities);
+
+      if (useMediaCapabilities) {
+        expect(variants[0].decodingInfos.length).toBe(2);
+      } else {
+        expect(requestMediaKeySystemAccessSpy).toHaveBeenCalledTimes(1);
+        // Although drm.def appears second in the manifest, it is queried first
+        // and also selected because it has a server configured.
+        const calls = requestMediaKeySystemAccessSpy.calls;
+        expect(calls.argsFor(0)[0]).toBe('drm.def');
+      }
+      expect(shaka.media.DrmEngine.keySystem(drmEngine.getDrmInfo()))
+          .toBe('drm.def');
+    });
+
     it('chooses systems with configured license servers', async () => {
       // Accept both drm.abc and drm.def.  Only one can be chosen.
       setRequestMediaKeySystemAccessSpy(['drm.abc', 'drm.def']);