diff --git a/.hgtags b/.hgtags
index 12f66e7785bd..6e4a99e69b32 100644
--- a/.hgtags
+++ b/.hgtags
@@ -269,3 +269,5 @@ f8fa7749f7bdc93fa3491918a4e8b0fb4db659eb FIREFOX_BETA_115_BASE
 7b63ca6bbdfaf5d4dc027f808de9f74789a5fa6e FIREFOX_NIGHTLY_117_END
 6aaf2cf582814f5a76c09fa2ac7cc760a5886134 FIREFOX_BETA_118_BASE
 1429ba8bcd5b6beb45399f77673bc59439db5d91 FIREFOX_NIGHTLY_118_END
+68035862c82691cc5ad039c1067c1fd24d048350 FIREFOX_BETA_119_BASE
+b8084fc54e158a2adcdac710ea0c3a7c9559309e FIREFOX_NIGHTLY_119_END
diff --git a/CLOBBER b/CLOBBER
index f97fd436d674..6d010e2b2f3e 100644
--- a/CLOBBER
+++ b/CLOBBER
@@ -22,4 +22,4 @@
 # changes to stick? As of bug 928195, this shouldn't be necessary! Please
 # don't change CLOBBER for WebIDL changes any more.
 
-Modified build files in third_party/libwebrtc - Bug 1774628 - re-enable support for Windows.Graphics.Capture APIs in libwebrtc. - moz.build file updates. r?pehrsons!
+Merge day clobber 2023-09-25
\ No newline at end of file
diff --git a/browser/config/version.txt b/browser/config/version.txt
index 97f671475e68..f5d18d2f71bc 100644
--- a/browser/config/version.txt
+++ b/browser/config/version.txt
@@ -1 +1 @@
-119.0a1
+120.0a1
diff --git a/browser/config/version_display.txt b/browser/config/version_display.txt
index 97f671475e68..f5d18d2f71bc 100644
--- a/browser/config/version_display.txt
+++ b/browser/config/version_display.txt
@@ -1 +1 @@
-119.0a1
+120.0a1
diff --git a/config/milestone.txt b/config/milestone.txt
index 22733cdfcf17..df7d85faf041 100644
--- a/config/milestone.txt
+++ b/config/milestone.txt
@@ -10,4 +10,4 @@
 # hardcoded milestones in the tree from these two files.
 #--------------------------------------------------------
 
-119.0a1
+120.0a1
diff --git a/services/sync/modules/constants.sys.mjs b/services/sync/modules/constants.sys.mjs
index 14c3cca87a72..c72d458b4521 100644
--- a/services/sync/modules/constants.sys.mjs
+++ b/services/sync/modules/constants.sys.mjs
@@ -4,7 +4,7 @@
 
 // Don't manually modify this line, as it is automatically replaced on merge day
 // by the gecko_migration.py script.
-export const WEAVE_VERSION = "1.121.0";
+export const WEAVE_VERSION = "1.122.0";
 
 // Sync Server API version that the client supports.
 export const SYNC_API_VERSION = "1.5";