diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index afd6b5968cafb720405c8243f9f0d9491a1bfd07..9d847c3025516f3225c60be7c492adff4d254e5b 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -63,6 +63,7 @@ void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
 	int pkt_len = skb->len - skb_inner_network_offset(skb);
 	struct net *net = dev_net(rt->dst.dev);
 	struct net_device *dev = skb->dev;
+	int skb_iif = skb->skb_iif;
 	struct iphdr *iph;
 	int err;
 
@@ -72,6 +73,14 @@ void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
 	skb_dst_set(skb, &rt->dst);
 	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
 
+	if (skb_iif && proto == IPPROTO_UDP) {
+		/* Arrived from an ingress interface and got udp encapuslated.
+		 * The encapsulated network segment length may exceed dst mtu.
+		 * Allow IP Fragmentation of segments.
+		 */
+		IPCB(skb)->flags |= IPSKB_FRAG_SEGS;
+	}
+
 	/* Push down and install the IP header. */
 	skb_push(skb, sizeof(struct iphdr));
 	skb_reset_network_header(skb);