diff --git a/CHANGELOG b/CHANGELOG
index 6416ee52..b9f0f98d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -13,6 +13,10 @@ HISTORY
 
   ++ New features:
 
+  2010-07-12: Simon Goldschmidt (patch by Stephane Lesage)
+  * ip.c, udp.c/.h, pbuf.h, sockets.c: task #10495: Added support for
+    IP_MULTICAST_LOOP at socket- and raw-API level.
+
   2010-06-16: Simon Goldschmidt
   * ip.c: Added an optional define (LWIP_IP_ACCEPT_UDP_PORT) that can allow
     link-layer-addressed UDP traffic to be received while a netif is down (just
diff --git a/src/api/sockets.c b/src/api/sockets.c
index e4b78f96..9919b611 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -1524,6 +1524,14 @@ lwip_getsockopt(int s, int level, int optname, void *optval, socklen_t *optlen)
         err = EINVAL;
       }
       break;
+    case IP_MULTICAST_LOOP:
+      if (*optlen < sizeof(u8_t)) {
+        err = EINVAL;
+      }
+      if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
+        err = EAFNOSUPPORT;
+      }
+      break;
 #endif /* LWIP_IGMP */
 
     default:
@@ -1738,6 +1746,15 @@ lwip_getsockopt_internal(void *arg)
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_IF) = 0x%"X32_F"\n",
                   s, *(u32_t *)optval));
       break;
+    case IP_MULTICAST_LOOP:
+      if ((sock->conn->pcb.udp->flags & UDP_FLAGS_MULTICAST_LOOP) != 0) {
+        *(u8_t*)optval = 1;
+      } else {
+        *(u8_t*)optval = 0;
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_LOOP) = %d\n",
+                  s, *(int *)optval));
+      break;
 #endif /* LWIP_IGMP */
     default:
       LWIP_ASSERT("unhandled optname", 0);
@@ -1906,6 +1923,14 @@ lwip_setsockopt(int s, int level, int optname, const void *optval, socklen_t opt
         err = EAFNOSUPPORT;
       }
       break;
+    case IP_MULTICAST_LOOP:
+      if (optlen < sizeof(u8_t)) {
+        err = EINVAL;
+      }
+      if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
+        err = EAFNOSUPPORT;
+      }
+      break;
     case IP_ADD_MEMBERSHIP:
     case IP_DROP_MEMBERSHIP:
       if (optlen < sizeof(struct ip_mreq)) {
@@ -2098,6 +2123,13 @@ lwip_setsockopt_internal(void *arg)
     case IP_MULTICAST_IF:
       inet_addr_to_ipaddr(&sock->conn->pcb.udp->multicast_ip, (struct in_addr*)optval);
       break;
+    case IP_MULTICAST_LOOP:
+      if (*(u8_t*)optval) {
+        udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_MULTICAST_LOOP);
+      } else {
+        udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_MULTICAST_LOOP);
+      }
+      break;
     case IP_ADD_MEMBERSHIP:
     case IP_DROP_MEMBERSHIP:
       {
diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index 59bcd24b..862c609d 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -710,13 +710,18 @@ err_t ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
     LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
     return netif_loop_output(netif, p, dest);
   }
+#if LWIP_IGMP
+  if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) {
+    netif_loop_output(netif, p, dest);
+  }
+#endif /* LWIP_IGMP */
 #endif /* ENABLE_LOOPBACK */
 #if IP_FRAG
   /* don't fragment if interface has mtu set to 0 [loopif] */
   if (netif->mtu && (p->tot_len > netif->mtu)) {
     return ip_frag(p, netif, dest);
   }
-#endif
+#endif /* IP_FRAG */
 
   LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
   return netif->output(netif, p, dest);
diff --git a/src/core/udp.c b/src/core/udp.c
index 0b335cda..e4dd44fb 100644
--- a/src/core/udp.c
+++ b/src/core/udp.c
@@ -540,6 +540,14 @@ udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
   /* in UDP, 0 checksum means 'no checksum' */
   udphdr->chksum = 0x0000; 
 
+  /* Multicast Loop? */
+#if LWIP_IGMP
+  if (ip_addr_ismulticast(dst_ip) && ((pcb->flags & UDP_FLAGS_MULTICAST_LOOP) != 0)) {
+    q->flags |= PBUF_FLAG_MCASTLOOP;
+  }
+#endif /* LWIP_IGMP */
+
+
   /* PCB local address is IP_ANY_ADDR? */
   if (ip_addr_isany(&pcb->local_ip)) {
     /* use outgoing network interface IP address as source address */
@@ -927,6 +935,10 @@ udp_new(void)
     /* initialize PCB to all zeroes */
     memset(pcb, 0, sizeof(struct udp_pcb));
     pcb->ttl = UDP_TTL;
+#if LWIP_IGMP
+    /* multicast loopback shall be turned on by default */
+    pcb->flags = PBUF_FLAG_MCASTLOOP;
+#endif /* LWIP_IGMP */
   }
   return pcb;
 }
diff --git a/src/include/lwip/pbuf.h b/src/include/lwip/pbuf.h
index 239edd77..3b1d608b 100644
--- a/src/include/lwip/pbuf.h
+++ b/src/include/lwip/pbuf.h
@@ -67,6 +67,8 @@ typedef enum {
 /** indicates this is a custom pbuf: pbuf_free and pbuf_header handle such a
     a pbuf differently */
 #define PBUF_FLAG_IS_CUSTOM 0x02U
+/** indicates this pbuf is UDP multicast to be looped back */
+#define PBUF_FLAG_MCASTLOOP 0x04U
 
 struct pbuf {
   /** next pbuf in singly linked pbuf chain */
diff --git a/src/include/lwip/udp.h b/src/include/lwip/udp.h
index ac1bb769..c98c1b3e 100644
--- a/src/include/lwip/udp.h
+++ b/src/include/lwip/udp.h
@@ -63,9 +63,10 @@ PACK_STRUCT_END
 #  include "arch/epstruct.h"
 #endif
 
-#define UDP_FLAGS_NOCHKSUM 0x01U
-#define UDP_FLAGS_UDPLITE  0x02U
-#define UDP_FLAGS_CONNECTED  0x04U
+#define UDP_FLAGS_NOCHKSUM       0x01U
+#define UDP_FLAGS_UDPLITE        0x02U
+#define UDP_FLAGS_CONNECTED      0x04U
+#define UDP_FLAGS_MULTICAST_LOOP 0x08U
 
 struct udp_pcb;