--- a/browser/confvars.sh
+++ b/browser/confvars.sh
@@ -51,18 +51,16 @@ MOZ_APP_ID={ec8030f7-c20a-464f-9b0e-13a3
 ACCEPTED_MAR_CHANNEL_IDS=firefox-mozilla-central
 # The MAR_CHANNEL_ID must not contain the following 3 characters: ",\t "
 MAR_CHANNEL_ID=firefox-mozilla-central
 MOZ_PROFILE_MIGRATOR=1
 MOZ_APP_STATIC_INI=1
 MOZ_WEBGL_CONFORMANT=1
 # Enable navigator.mozPay
 MOZ_PAY=1
-# Enable activities. These are used for FxOS developers currently.
-MOZ_ACTIVITIES=1
 MOZ_JSDOWNLOADS=1
 MOZ_RUST_MP4PARSE=1
 
 # Enable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=1
 
 # Include the DevTools client, not just the server (which is the default)
 MOZ_DEVTOOLS=all

--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -170,20 +170,16 @@
 #ifdef MOZ_WEBRTC
 @RESPATH@/components/content_webrtc.xpt
 #endif
 @RESPATH@/components/content_xslt.xpt
 @RESPATH@/components/cookie.xpt
 @RESPATH@/components/directory.xpt
 @RESPATH@/components/docshell.xpt
 @RESPATH@/components/dom.xpt
-#ifdef MOZ_ACTIVITIES
-@RESPATH@/components/dom_activities.xpt
-@RESPATH@/components/dom_messages.xpt
-#endif
 @RESPATH@/components/dom_apps.xpt
 @RESPATH@/components/dom_newapps.xpt
 @RESPATH@/components/dom_base.xpt
 @RESPATH@/components/dom_system.xpt
 #ifdef MOZ_B2G_BT
 @RESPATH@/components/dom_bluetooth.xpt
 #endif
 @RESPATH@/components/dom_canvas.xpt
@@ -532,29 +528,16 @@
 @RESPATH@/components/RemoteWebNavigation.js
 
 @RESPATH@/components/SlowScriptDebug.manifest
 @RESPATH@/components/SlowScriptDebug.js
 
 @RESPATH@/components/TVSimulatorService.js
 @RESPATH@/components/TVSimulatorService.manifest
 
-#ifdef MOZ_ACTIVITIES
-@RESPATH@/components/SystemMessageCache.js
-@RESPATH@/components/SystemMessageInternal.js
-@RESPATH@/components/SystemMessageManager.js
-@RESPATH@/components/SystemMessageManager.manifest
-
-@RESPATH@/components/Activities.manifest
-@RESPATH@/components/ActivityProxy.js
-@RESPATH@/components/ActivityRequestHandler.js
-@RESPATH@/components/ActivityWrapper.js
-@RESPATH@/components/ActivityMessageConfigurator.js
-#endif
-
 @RESPATH@/components/Payment.js
 @RESPATH@/components/PaymentFlowInfo.js
 @RESPATH@/components/Payment.manifest
 
 #ifdef MOZ_WEBRTC
 @RESPATH@/components/PeerConnection.js
 @RESPATH@/components/PeerConnection.manifest
 #endif

--- a/old-configure.in
+++ b/old-configure.in
@@ -5704,24 +5704,16 @@ dnl ====================================
 dnl = Enable Support for Payment API
 dnl ========================================================
 if test -n "$MOZ_PAY"; then
     AC_DEFINE(MOZ_PAY)
 fi
 AC_SUBST(MOZ_PAY)
 
 dnl ========================================================
-dnl = Enable Browser Support for Activities
-dnl ========================================================
-if test -n "$MOZ_ACTIVITIES"; then
-    AC_DEFINE(MOZ_ACTIVITIES)
-fi
-AC_SUBST(MOZ_ACTIVITIES)
-
-dnl ========================================================
 dnl = Enable Support for AudioChannelManager API
 dnl ========================================================
 if test -n "$MOZ_AUDIO_CHANNEL_MANAGER"; then
     AC_DEFINE(MOZ_AUDIO_CHANNEL_MANAGER)
 fi
 AC_SUBST(MOZ_AUDIO_CHANNEL_MANAGER)
 
 dnl ========================================================