diff --git a/irc/caps/constants.go b/irc/caps/constants.go
index 324f443c..f8a3d5d1 100644
--- a/irc/caps/constants.go
+++ b/irc/caps/constants.go
@@ -58,6 +58,8 @@ const (
 	// More draft names associated with draft/multiline:
 	MultilineBatchType = "draft/multiline"
 	MultilineConcatTag = "draft/multiline-concat"
+	// draft/relaymsg:
+	RelaymsgTagName = "draft/relaymsg"
 )
 
 func init() {
diff --git a/irc/handlers.go b/irc/handlers.go
index 4b3464b0..a1756a25 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -2587,7 +2587,10 @@ func relaymsgHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *
 	// send msg
 	channelName := channel.Name()
 	relayTags := map[string]string{
-		"relaymsg": client.Nick(),
+		caps.RelaymsgTagName: client.Nick(),
+	}
+	for t, v := range msg.ClientOnlyTags() {
+		relayTags[t] = v
 	}
 	for _, member := range channel.Members() {
 		for _, session := range member.Sessions() {
diff --git a/irctest b/irctest
index 307722fb..b58fe44b 160000
--- a/irctest
+++ b/irctest
@@ -1 +1 @@
-Subproject commit 307722fbecc5ab69ee3246153b8f8f91ad830830
+Subproject commit b58fe44b5b36e9bf07af9b5a0033455524e2b456