diff --git a/mysql-test/Makefile.am b/mysql-test/Makefile.am
index ba96c5947ba..8b0c096120a 100644
--- a/mysql-test/Makefile.am
+++ b/mysql-test/Makefile.am
@@ -32,6 +32,7 @@ dist-hook:
 	$(INSTALL_DATA) $(srcdir)/r/*.result $(srcdir)/r/*.require $(distdir)/r
 	$(INSTALL_DATA) $(srcdir)/std_data/*.dat $(srcdir)/std_data/*.001 $(distdir)/std_data
 	$(INSTALL_DATA) $(srcdir)/std_data/des_key_file $(distdir)/std_data
+	$(INSTALL_DATA) $(srcdir)/std_data/Moscow_leap $(distdir)/std_data
 
 install-data-local:
 	$(mkinstalldirs) \
@@ -50,6 +51,7 @@ install-data-local:
 	$(INSTALL_DATA) $(srcdir)/std_data/*.dat $(DESTDIR)$(testdir)/std_data
 	$(INSTALL_DATA) $(srcdir)/std_data/*.*001 $(DESTDIR)$(testdir)/std_data
 	$(INSTALL_DATA) $(srcdir)/std_data/des_key_file $(DESTDIR)$(testdir)/std_data
+	$(INSTALL_DATA) $(srcdir)/std_data/Moscow_leap $(DESTDIR)$(testdir)/std_data
 
 SUFFIXES = .sh
 
diff --git a/mysql-test/r/have_moscow_leap_timezone.require b/mysql-test/r/have_moscow_leap_timezone.require
new file mode 100644
index 00000000000..f27452d7770
--- /dev/null
+++ b/mysql-test/r/have_moscow_leap_timezone.require
@@ -0,0 +1,2 @@
+from_unixtime(1072904422)
+2004-01-01 00:00:00
diff --git a/mysql-test/r/timezone3.result b/mysql-test/r/timezone3.result
new file mode 100644
index 00000000000..2135dd33511
--- /dev/null
+++ b/mysql-test/r/timezone3.result
@@ -0,0 +1,41 @@
+drop table if exists t1;
+create table t1 (i int, c varchar(20));
+insert into t1 values
+(unix_timestamp("2004-01-01 00:00:00"), "2004-01-01 00:00:00");
+insert into t1 values
+(unix_timestamp("2004-03-28 01:59:59"), "2004-03-28 01:59:59"),
+(unix_timestamp("2004-03-28 02:30:00"), "2004-03-28 02:30:00"),
+(unix_timestamp("2004-03-28 03:00:00"), "2004-03-28 03:00:00");
+insert into t1 values
+(unix_timestamp('2004-05-01 00:00:00'),'2004-05-01 00:00:00');
+insert into t1 values
+(unix_timestamp('2004-10-31 01:00:00'),'2004-10-31 01:00:00'),
+(unix_timestamp('2004-10-31 02:00:00'),'2004-10-31 02:00:00'),
+(unix_timestamp('2004-10-31 02:59:59'),'2004-10-31 02:59:59'),
+(unix_timestamp('2004-10-31 04:00:00'),'2004-10-31 04:00:00'),
+(unix_timestamp('2004-10-31 02:59:59'),'2004-10-31 02:59:59');
+insert into t1 values
+(unix_timestamp('1981-07-01 03:59:59'),'1981-07-01 03:59:59'),
+(unix_timestamp('1981-07-01 04:00:00'),'1981-07-01 04:00:00');
+select i, from_unixtime(i), c from t1;
+i	from_unixtime(i)	c
+1072904422	2004-01-01 00:00:00	2004-01-01 00:00:00
+1080428421	2004-03-28 01:59:59	2004-03-28 01:59:59
+1080428422	2004-03-28 03:00:00	2004-03-28 02:30:00
+1080428422	2004-03-28 03:00:00	2004-03-28 03:00:00
+1083355222	2004-05-01 00:00:00	2004-05-01 00:00:00
+1099170022	2004-10-31 01:00:00	2004-10-31 01:00:00
+1099177222	2004-10-31 02:00:00	2004-10-31 02:00:00
+1099180821	2004-10-31 02:59:59	2004-10-31 02:59:59
+1099184422	2004-10-31 04:00:00	2004-10-31 04:00:00
+1099180821	2004-10-31 02:59:59	2004-10-31 02:59:59
+362793608	1981-07-01 03:59:59	1981-07-01 03:59:59
+362793610	1981-07-01 04:00:00	1981-07-01 04:00:00
+drop table t1;
+create table t1 (ts timestamp);
+insert into t1 values (19730101235900), (20040101235900);
+select * from t1;
+ts
+19730101235900
+20040101235900
+drop table t1;
diff --git a/mysql-test/std_data/Moscow_leap b/mysql-test/std_data/Moscow_leap
new file mode 100644
index 00000000000..4994c005595
Binary files /dev/null and b/mysql-test/std_data/Moscow_leap differ
diff --git a/mysql-test/t/timezone3-master.opt b/mysql-test/t/timezone3-master.opt
new file mode 100644
index 00000000000..6910e6e6e8d
--- /dev/null
+++ b/mysql-test/t/timezone3-master.opt
@@ -0,0 +1 @@
+--timezone=:$MYSQL_TEST_DIR/std_data/Moscow_leap
diff --git a/mysql-test/t/timezone3.test b/mysql-test/t/timezone3.test
new file mode 100644
index 00000000000..8910783cd85
--- /dev/null
+++ b/mysql-test/t/timezone3.test
@@ -0,0 +1,59 @@
+#
+# Test of handling time zone with leap seconds.
+#
+# This test should be run with TZ=:$MYSQL_TEST_DIR/std_data/Moscow_leap
+# This implies that this test should be run only on systems that interpret 
+# characters after colon in TZ variable as path to zoneinfo file.
+#
+# Check that we have successfully set time zone with leap seconds.
+--require r/have_moscow_leap_timezone.require
+disable_query_log;
+select from_unixtime(1072904422);
+enable_query_log;
+
+# Initial clean-up
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+
+#
+# Let us check behavior of conversion from broken-down representation
+# to time_t representation, for normal, non-existent and ambigious dates
+# (This check is similar to the one in timezone2.test in 4.1)
+#
+create table t1 (i int, c varchar(20));
+# Normal value without DST
+insert into t1 values
+  (unix_timestamp("2004-01-01 00:00:00"), "2004-01-01 00:00:00");
+# Values around and in spring time-gap
+insert into t1 values
+  (unix_timestamp("2004-03-28 01:59:59"), "2004-03-28 01:59:59"),
+  (unix_timestamp("2004-03-28 02:30:00"), "2004-03-28 02:30:00"),
+  (unix_timestamp("2004-03-28 03:00:00"), "2004-03-28 03:00:00");
+# Normal value with DST
+insert into t1 values
+  (unix_timestamp('2004-05-01 00:00:00'),'2004-05-01 00:00:00');
+# Ambiguos values (also check for determenism)
+insert into t1 values
+  (unix_timestamp('2004-10-31 01:00:00'),'2004-10-31 01:00:00'),
+  (unix_timestamp('2004-10-31 02:00:00'),'2004-10-31 02:00:00'),
+  (unix_timestamp('2004-10-31 02:59:59'),'2004-10-31 02:59:59'),
+  (unix_timestamp('2004-10-31 04:00:00'),'2004-10-31 04:00:00'),
+  (unix_timestamp('2004-10-31 02:59:59'),'2004-10-31 02:59:59');
+# Test of leap
+insert into t1 values
+  (unix_timestamp('1981-07-01 03:59:59'),'1981-07-01 03:59:59'),
+  (unix_timestamp('1981-07-01 04:00:00'),'1981-07-01 04:00:00');
+
+select i, from_unixtime(i), c from t1;
+drop table t1;
+
+#
+# Test for bug #6387 "Queried timestamp values do not match the 
+# inserted". my_gmt_sec() function was not working properly if we
+# had time zone with leap seconds 
+#
+create table t1 (ts timestamp);
+insert into t1 values (19730101235900), (20040101235900);
+select * from t1;
+drop table t1;
diff --git a/sql/time.cc b/sql/time.cc
index 0363d764100..38670db054f 100644
--- a/sql/time.cc
+++ b/sql/time.cc
@@ -81,6 +81,10 @@ long my_gmt_sec(TIME *t, long *my_timezone)
     I couldn't come up with a better way to get a repeatable result :(
 
     We can't use mktime() as it's buggy on many platforms and not thread safe.
+
+    Note: this code assumes that our time_t estimation is not too far away
+    from real value (we assume that localtime_r(tmp) will return something
+    within 24 hrs from t) which is probably true for all current time zones.
   */
   tmp=(time_t) (((calc_daynr((uint) t->year,(uint) t->month,(uint) t->day) -
 		  (long) days_at_timestart)*86400L + (long) t->hour*3600L +
@@ -93,7 +97,8 @@ long my_gmt_sec(TIME *t, long *my_timezone)
   for (loop=0;
        loop < 2 &&
 	 (t->hour != (uint) l_time->tm_hour ||
-	  t->minute != (uint) l_time->tm_min);
+          t->minute != (uint) l_time->tm_min ||
+          t->second != (uint) l_time->tm_sec);
        loop++)
   {					/* One check should be enough ? */
     /* Get difference in days */
@@ -103,15 +108,22 @@ long my_gmt_sec(TIME *t, long *my_timezone)
     else if (days > 1)
       days= -1;
     diff=(3600L*(long) (days*24+((int) t->hour - (int) l_time->tm_hour)) +
-	  (long) (60*((int) t->minute - (int) l_time->tm_min)));
+          (long) (60*((int) t->minute - (int) l_time->tm_min)) +
+          (long) ((int) t->second - (int) l_time->tm_sec));
     current_timezone+= diff+3600;		// Compensate for -3600 above
     tmp+= (time_t) diff;
     localtime_r(&tmp,&tm_tmp);
     l_time=&tm_tmp;
   }
   /*
-    Fix that if we are in the not existing daylight saving time hour
-    we move the start of the next real hour
+    Fix that if we are in the non existing daylight saving time hour
+    we move the start of the next real hour.
+
+    This code doesn't handle such exotical thing as time-gaps whose length
+    is more than one hour or non-integer (latter can theoretically happen
+    if one of seconds will be removed due leap correction, or because of
+    general time correction like it happened for Africa/Monrovia time zone
+    in year 1972).
   */
   if (loop == 2 && t->hour != (uint) l_time->tm_hour)
   {
@@ -121,7 +133,8 @@ long my_gmt_sec(TIME *t, long *my_timezone)
     else if (days > 1)
       days= -1;
     diff=(3600L*(long) (days*24+((int) t->hour - (int) l_time->tm_hour))+
-	  (long) (60*((int) t->minute - (int) l_time->tm_min)));
+	  (long) (60*((int) t->minute - (int) l_time->tm_min)) +
+          (long) ((int) t->second - (int) l_time->tm_sec));
     if (diff == 3600)
       tmp+=3600 - t->minute*60 - t->second;	// Move to next hour
     else if (diff == -3600)