diff --git a/drivers/mailbox/mailbox-uclass.c b/drivers/mailbox/mailbox-uclass.c
index 822ae5b..e149bf5 100644
--- a/drivers/mailbox/mailbox-uclass.c
+++ b/drivers/mailbox/mailbox-uclass.c
@@ -100,13 +100,29 @@ int mbox_free(struct mbox_chan *chan)
 	return ops->free(chan);
 }
 
-int mbox_send(struct mbox_chan *chan, const void *data)
+int mbox_send(struct mbox_chan *chan, const void *data, ulong timeout_us)
 {
 	struct mbox_ops *ops = mbox_dev_ops(chan->dev);
+	ulong start_time;
+	int ret;
 
 	debug("%s(chan=%p, data=%p)\n", __func__, chan, data);
 
-	return ops->send(chan, data);
+	start_time = timer_get_us();
+	/*
+	 * Account for partial us ticks, but if timeout_us is 0, ensure we
+	 * still don't wait at all.
+	 */
+	if (timeout_us)
+		timeout_us++;
+
+	for (;;) {
+		ret = ops->send(chan, data);
+		if (ret != -EBUSY)
+			return ret;
+		if ((timer_get_us() - start_time) >= timeout_us)
+			return -ETIMEDOUT;
+	}
 }
 
 int mbox_recv(struct mbox_chan *chan, void *data, ulong timeout_us)
diff --git a/include/mailbox.h b/include/mailbox.h
index a92a1a5..8d89f3f 100644
--- a/include/mailbox.h
+++ b/include/mailbox.h
@@ -124,7 +124,7 @@ int mbox_free(struct mbox_chan *chan);
  *		will ignore this parameter.
  * @return 0 if OK, or a negative error code.
  */
-int mbox_send(struct mbox_chan *chan, const void *data);
+int mbox_send(struct mbox_chan *chan, const void *data, ulong timeout_us);
 
 /**
  * mbox_recv - Receive any available message from a mailbox channel