diff --git a/CHANGES b/CHANGES
index 0a92707757..fbd6bf4267 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4093.	[func]		Dig now learns the SIT value from truncated
+			responses when it retries over TCP. [RT #39047]
+
 4092.	[bug]		'in-view' didn't work for zones beneath a empty zone.
 			[RT #39173]
 
diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index f72925ef4a..35a86b3223 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -149,6 +149,10 @@ int ndots = -1;
 int tries = 3;
 int lookup_counter = 0;
 
+#ifdef ISC_PLATFORM_USESIT
+static char sitvalue[256];
+#endif
+
 #ifdef WITH_IDN
 static void		initialize_idn(void);
 static isc_result_t	output_filter(isc_buffer_t *buffer,
@@ -3412,6 +3416,7 @@ process_sit(dig_lookup_t *l, dns_message_t *msg,
 	isc_buffer_t hexbuf;
 	size_t len;
 	const unsigned char *sit;
+	isc_boolean_t copysit;
 	isc_result_t result;
 
 	if (l->sitvalue != NULL) {
@@ -3420,9 +3425,11 @@ process_sit(dig_lookup_t *l, dns_message_t *msg,
 		check_result(result, "isc_hex_decodestring");
 		sit = isc_buffer_base(&hexbuf);
 		len = isc_buffer_usedlength(&hexbuf);
+		copysit = ISC_FALSE;
 	} else {
 		sit = cookie;
 		len = sizeof(cookie);
+		copysit = ISC_TRUE;
 	}
 
 	INSIST(msg->sitok == 0 && msg->sitbad == 0);
@@ -3432,10 +3439,25 @@ process_sit(dig_lookup_t *l, dns_message_t *msg,
 		} else {
 			printf(";; Warning: SIT client cookie mismatch\n");
 			msg->sitbad = 1;
+			copysit = ISC_FALSE;
 		}
 	} else {
 		printf(";; Warning: SIT bad token (too short)\n");
 		msg->sitbad = 1;
+		copysit = ISC_FALSE;
+	}
+	if (copysit) {
+		isc_region_t r;
+
+		r.base = isc_buffer_current(optbuf);
+		r.length = (unsigned int)optlen;
+		isc_buffer_init(&hexbuf, sitvalue, sizeof(sitvalue));
+		result = isc_hex_totext(&r, 2, "", &hexbuf);
+		check_result(result, "isc_hex_totext");
+		if (isc_buffer_availablelength(&hexbuf) > 0) {
+			isc_buffer_putuint8(&hexbuf, 0);
+			l->sitvalue = sitvalue;
+		}
 	}
 	isc_buffer_forward(optbuf, (unsigned int)optlen);
 }
@@ -3756,6 +3778,10 @@ recv_done(isc_task_t *task, isc_event_t *event) {
 	}
 	if ((msg->flags & DNS_MESSAGEFLAG_TC) != 0 &&
 	    !l->ignore && !l->tcp_mode) {
+#ifdef ISC_PLATFORM_USESIT
+		if (l->sitvalue == NULL && l->sit && msg->opt != NULL)
+			process_opt(l, msg);
+#endif
 		if (l->comments)
 			printf(";; Truncated, retrying in TCP mode.\n");
 		n = requeue_lookup(l, ISC_TRUE);
diff --git a/bin/tests/system/sit/tests.sh b/bin/tests/system/sit/tests.sh
index 5842a98714..5f619e6863 100755
--- a/bin/tests/system/sit/tests.sh
+++ b/bin/tests/system/sit/tests.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# Copyright (C) 2014  Internet Systems Consortium, Inc. ("ISC")
+# Copyright (C) 2014, 2015  Internet Systems Consortium, Inc. ("ISC")
 #
 # Permission to use, copy, modify, and/or distribute this software for any
 # purpose with or without fee is hereby granted, provided that the above
@@ -28,6 +28,12 @@ getsit() {
 	}' < $1
 }
 
+fullsit() {
+	awk 'BEGIN { n = 0 }
+	     // { v[n++] = length(); }
+	     END { print (v[1] == v[2]); }'
+}
+
 havetc() {
 	grep 'flags:.* tc[^;]*;' $1 > /dev/null
 }
@@ -87,6 +93,17 @@ grep "; SIT:.*(good)" dig.out.test$n > /dev/null || ret=1
 if [ $ret != 0 ]; then echo "I:failed"; fi
 status=`expr $status + $ret`
 
+n=`expr $n + 1`
+echo "I:checking SIT is learnt for TCP retry ($n)"
+ret=0
+$DIG +qr +sit large.example txt @10.53.0.1 -p 5300 > dig.out.test$n
+linecount=`getsit dig.out.test$n | wc -l`
+if [ $linecount != 3 ]; then ret=1; fi
+checkfull=`getsit dig.out.test$n | fullsit`
+if [ $checkfull != 1 ]; then ret=1; fi
+if [ $ret != 0 ]; then echo "I:failed"; fi
+status=`expr $status + $ret`
+
 n=`expr $n + 1`
 echo "I:checking for SIT value in adb ($n)"
 ret=0
diff --git a/doc/arm/notes.xml b/doc/arm/notes.xml
index 8bcc72528c..624e9d417f 100644
--- a/doc/arm/notes.xml
+++ b/doc/arm/notes.xml
@@ -459,6 +459,14 @@
 	  [RT #37927]
 	</para>
       </listitem>
+      <listitem>
+	<para>
+	  When retrying a query via TCP due to the first answer being
+	  truncated, <command>dig</command> will now correctly send
+	  the SIT (server identity token) value returned by the server
+	  in the prior response. [RT #39047]
+	</para>
+      </listitem>
     </itemizedlist>
   </sect2>
   <sect2 id="relnotes_bugs">