diff --git a/src/cluster.c b/src/cluster.c
index 66cfe4ff64da1886b7add599d54a428e97ebfcb0..6586a6ce0249c0d3c65702880457e21190d7a24d 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -3274,6 +3274,10 @@ socket_rd_err:
     return;
 }
 
+/* -----------------------------------------------------------------------------
+ * Cluster functions related to serving / redirecting clients
+ * -------------------------------------------------------------------------- */
+
 /* The ASKING command is required after a -ASK redirection.
  * The client should issue ASKING before to actually send the command to
  * the target instance. See the Redis Cluster specification for more
@@ -3287,9 +3291,23 @@ void askingCommand(redisClient *c) {
     addReply(c,shared.ok);
 }
 
-/* -----------------------------------------------------------------------------
- * Cluster functions related to serving / redirecting clients
- * -------------------------------------------------------------------------- */
+/* The READONLY command is uesd by clients to enter the read-only mode.
+ * In this mode slaves will not redirect clients as long as clients access
+ * with read-only commands to keys that are served by the slave's master. */
+void readonlyCommand(redisClient *c) {
+    if (server.cluster_enabled == 0) {
+        addReplyError(c,"This instance has cluster support disabled");
+        return;
+    }
+    c->flags |= REDIS_READONLY;
+    addReply(c,shared.ok);
+}
+
+/* The READWRITE command just clears the READONLY command state. */
+void readwriteCommand(redisClient *c) {
+    c->flags &= ~REDIS_READONLY;
+    addReply(c,shared.ok);
+}
 
 /* Return the pointer to the cluster node that is able to serve the command.
  * For the function to succeed the command should only target a single
@@ -3385,6 +3403,16 @@ clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **arg
         (c->flags & REDIS_ASKING || cmd->flags & REDIS_CMD_ASKING)) {
         return server.cluster->myself;
     }
+    /* Handle the read-only client case reading from a slave: if this
+     * node is a slave and the request is about an hash slot our master
+     * is serving, we can reply without redirection. */
+    if (c->flags & REDIS_READONLY &&
+        cmd->flags & REDIS_CMD_READONLY &&
+        server.cluster->myself->flags & REDIS_NODE_SLAVE &&
+        server.cluster->myself->slaveof == n)
+    {
+        return server.cluster->myself;
+    }
     /* It's not a -ASK case. Base case: just return the right node. */
     return n;
 }
diff --git a/src/networking.c b/src/networking.c
index ff3681f52f535cb47470938f972231ff55849da8..bf16559acbc46f1337d24fd3eac8bc568f0601ea 100644
--- a/src/networking.c
+++ b/src/networking.c
@@ -1263,6 +1263,7 @@ sds getClientInfoString(redisClient *client) {
     if (client->flags & REDIS_UNBLOCKED) *p++ = 'u';
     if (client->flags & REDIS_CLOSE_ASAP) *p++ = 'A';
     if (client->flags & REDIS_UNIX_SOCKET) *p++ = 'U';
+    if (client->flags & REDIS_READONLY) *p++ = 'r';
     if (p == flags) *p++ = 'N';
     *p++ = '\0';
 
diff --git a/src/redis.c b/src/redis.c
index e926e9c8db97c7f43506799e0d45d77814793c6a..ef07d9b25c21e9739a1dd6261065011cf4807a61 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -254,6 +254,8 @@ struct redisCommand redisCommandTable[] = {
     {"restore-asking",restoreCommand,-4,"awmk",0,NULL,1,1,1,0,0},
     {"migrate",migrateCommand,-6,"aw",0,NULL,0,0,0,0,0},
     {"asking",askingCommand,1,"r",0,NULL,0,0,0,0,0},
+    {"readonly",readonlyCommand,1,"r",0,NULL,0,0,0,0,0},
+    {"readwrite",readwriteCommand,1,"r",0,NULL,0,0,0,0,0},
     {"dump",dumpCommand,2,"ar",0,NULL,1,1,1,0,0},
     {"object",objectCommand,-2,"r",0,NULL,2,2,2,0,0},
     {"client",clientCommand,-2,"ar",0,NULL,0,0,0,0,0},
diff --git a/src/redis.h b/src/redis.h
index ace974ee1563e8f860d20ef815abd12209a4e52a..0a7bc0960f3b07c34e3f607276185d09fe7597d0 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -232,6 +232,7 @@
 #define REDIS_FORCE_AOF (1<<14)   /* Force AOF propagation of current cmd. */
 #define REDIS_FORCE_REPL (1<<15)  /* Force replication of current cmd. */
 #define REDIS_PRE_PSYNC (1<<16)   /* Instance don't understand PSYNC. */
+#define REDIS_READONLY (1<<17)    /* Cluster client is in read-only state. */
 
 /* Client block type (btype field in client structure)
  * if REDIS_BLOCKED flag is set. */
@@ -1397,6 +1398,8 @@ void clusterCommand(redisClient *c);
 void restoreCommand(redisClient *c);
 void migrateCommand(redisClient *c);
 void askingCommand(redisClient *c);
+void readonlyCommand(redisClient *c);
+void readwriteCommand(redisClient *c);
 void dumpCommand(redisClient *c);
 void objectCommand(redisClient *c);
 void clientCommand(redisClient *c);