diff --git a/irc/capability.go b/irc/capability.go
index 3cab24c9..1849040b 100644
--- a/irc/capability.go
+++ b/irc/capability.go
@@ -23,7 +23,7 @@ const (
 	ExtendedJoin    Capability = "extended-join"
 	InviteNotify    Capability = "invite-notify"
 	MaxLine         Capability = "draft/maxline"
-	MessageTags     Capability = "draft/message-tags"
+	MessageTags     Capability = "draft/message-tags-0.2"
 	MultiPrefix     Capability = "multi-prefix"
 	SASL            Capability = "sasl"
 	ServerTime      Capability = "server-time"
diff --git a/irc/client.go b/irc/client.go
index 2e8a8c51..70985f85 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -135,6 +135,21 @@ func NewClient(server *Server, conn net.Conn, isTLS bool) *Client {
 // command goroutine
 //
 
+func (client *Client) maxlens() (int, int) {
+	maxlenTags := 512
+	maxlenRest := 512
+	if client.capabilities[MessageTags] {
+		maxlenTags = 4096
+	}
+	if client.capabilities[MaxLine] {
+		if maxLineTagsLength > maxlenTags {
+			maxlenTags = maxLineTagsLength
+		}
+		maxlenRest = maxLineRestLength
+	}
+	return maxlenTags, maxlenRest
+}
+
 func (client *Client) run() {
 	var err error
 	var isExiting bool
@@ -152,14 +167,9 @@ func (client *Client) run() {
 			break
 		}
 
-		var maxLen int
-		if client.capabilities[MaxLine] {
-			maxLen = maxLineLength
-		} else {
-			maxLen = 512
-		}
+		maxlenTags, maxlenRest := client.maxlens()
 
-		msg, err = ircmsg.ParseLineMaxLen(line, maxLen)
+		msg, err = ircmsg.ParseLineMaxLen(line, maxlenTags, maxlenRest)
 		if err != nil {
 			client.Quit("received malformed line")
 			break
@@ -512,16 +522,10 @@ func (client *Client) Send(tags *map[string]ircmsg.TagValue, prefix string, comm
 		}
 	}
 
-	var maxLen int
-	if client.capabilities[MaxLine] {
-		maxLen = maxLineLength
-	} else {
-		maxLen = 512
-	}
-
 	// send out the message
 	message := ircmsg.MakeMessage(tags, prefix, command, params...)
-	line, err := message.LineMaxLen(maxLen)
+	maxlenTags, maxlenRest := client.maxlens()
+	line, err := message.LineMaxLen(maxlenTags, maxlenRest)
 	if err != nil {
 		// try not to fail quietly - especially useful when running tests, as a note to dig deeper
 		// log.Println("Error assembling message:")
diff --git a/irc/config.go b/irc/config.go
index f840e8b9..0a689026 100644
--- a/irc/config.go
+++ b/irc/config.go
@@ -116,6 +116,11 @@ type ConnectionThrottleConfig struct {
 	Exempted           []string
 }
 
+type LineLenConfig struct {
+	Tags int
+	Rest int
+}
+
 type Config struct {
 	Network struct {
 		Name string
@@ -151,15 +156,15 @@ type Config struct {
 	Opers map[string]*OperConfig
 
 	Limits struct {
-		AwayLen        uint `yaml:"awaylen"`
-		ChanListModes  uint `yaml:"chan-list-modes"`
-		ChannelLen     uint `yaml:"channellen"`
-		KickLen        uint `yaml:"kicklen"`
-		LineLen        uint `yaml:"linelen"`
-		MonitorEntries uint `yaml:"monitor-entries"`
-		NickLen        uint `yaml:"nicklen"`
-		TopicLen       uint `yaml:"topiclen"`
-		WhowasEntries  uint `yaml:"whowas-entries"`
+		AwayLen        uint          `yaml:"awaylen"`
+		ChanListModes  uint          `yaml:"chan-list-modes"`
+		ChannelLen     uint          `yaml:"channellen"`
+		KickLen        uint          `yaml:"kicklen"`
+		MonitorEntries uint          `yaml:"monitor-entries"`
+		NickLen        uint          `yaml:"nicklen"`
+		TopicLen       uint          `yaml:"topiclen"`
+		WhowasEntries  uint          `yaml:"whowas-entries"`
+		LineLen        LineLenConfig `yaml:"linelen"`
 	}
 }
 
@@ -336,7 +341,7 @@ func LoadConfig(filename string) (config *Config, err error) {
 			return nil, fmt.Errorf("Could not parse connection-throttle ban-duration: %s", err.Error())
 		}
 	}
-	if config.Limits.LineLen < 512 {
+	if config.Limits.LineLen.Tags < 512 || config.Limits.LineLen.Rest < 512 {
 		return nil, errors.New("Line length must be 512 or greater")
 	}
 
diff --git a/irc/constants.go b/irc/constants.go
index 354be513..c8468cce 100644
--- a/irc/constants.go
+++ b/irc/constants.go
@@ -17,7 +17,8 @@ var (
 	Ver = fmt.Sprintf("oragono-%s", SemVer)
 
 	// Used as the standard maximum line length unless overridden at runtime.
-	maxLineLength = 512
+	maxLineTagsLength = 512
+	maxLineRestLength = 512
 	// maxLastArgLength is used to simply cap off the final argument when creating general messages where we need to select a limit.
 	// for instance, in MONITOR lists, RPL_ISUPPORT lists, etc.
 	maxLastArgLength = 400
diff --git a/irc/server.go b/irc/server.go
index d9f7f649..74c930f5 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -37,7 +37,7 @@ var (
 	errDbOutOfDate = errors.New("Database schema is old.")
 )
 
-// Limits holds the maximum limits for various things such as topic lengths
+// Limits holds the maximum limits for various things such as topic lengths.
 type Limits struct {
 	AwayLen        int
 	ChannelLen     int
@@ -46,7 +46,13 @@ type Limits struct {
 	NickLen        int
 	TopicLen       int
 	ChanListModes  int
-	LineLen        int
+	LineLen        LineLenLimits
+}
+
+// LineLenLimits holds the maximum limits for IRC lines.
+type LineLenLimits struct {
+	Tags int
+	Rest int
 }
 
 // ListenerInterface represents an interface for a listener.
@@ -147,10 +153,9 @@ func NewServer(configFilename string, config *Config) *Server {
 		SupportedCapabilities[SASL] = true
 	}
 
-	if config.Limits.LineLen > 512 {
-		maxLineLength = int(config.Limits.LineLen)
+	if config.Limits.LineLen.Tags > 512 || config.Limits.LineLen.Rest > 512 {
 		SupportedCapabilities[MaxLine] = true
-		CapValues[MaxLine] = strconv.Itoa(int(config.Limits.LineLen))
+		CapValues[MaxLine] = fmt.Sprintf("%d,%d", config.Limits.LineLen.Tags, config.Limits.LineLen.Rest)
 	}
 
 	operClasses, err := config.OperatorClasses()
@@ -191,7 +196,10 @@ func NewServer(configFilename string, config *Config) *Server {
 			NickLen:        int(config.Limits.NickLen),
 			TopicLen:       int(config.Limits.TopicLen),
 			ChanListModes:  int(config.Limits.ChanListModes),
-			LineLen:        int(config.Limits.LineLen),
+			LineLen: LineLenLimits{
+				Tags: config.Limits.LineLen.Tags,
+				Rest: config.Limits.LineLen.Rest,
+			},
 		},
 		listeners:      make(map[string]ListenerInterface),
 		monitoring:     make(map[string][]Client),
@@ -1108,7 +1116,7 @@ func (server *Server) rehash() error {
 	}
 
 	// line lengths cannot be changed after launching the server
-	if maxLineLength != int(config.Limits.LineLen) {
+	if maxLineTagsLength != config.Limits.LineLen.Tags || maxLineRestLength != config.Limits.LineLen.Rest {
 		return fmt.Errorf("Maximum line length (linelen) cannot be changed after launching the server, rehash aborted")
 	}
 
diff --git a/oragono.yaml b/oragono.yaml
index 2875eb4f..9885298e 100644
--- a/oragono.yaml
+++ b/oragono.yaml
@@ -204,4 +204,9 @@ limits:
     chan-list-modes: 60
 
     # maximum length of IRC lines
-    linelen: 2048
+    linelen:
+        # tags section
+        tags: 2048
+
+        # rest of the message
+        rest: 2048