diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 0b19cddf54..6a10488d9a 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -1812,9 +1812,35 @@ DetermineTimeZoneAbbrevOffsetTS(TimestampTz ts, const char *abbr,
 }
 
 
+/* TimeZoneAbbrevIsKnown()
+ *
+ * Detect whether the given string is a time zone abbreviation that's known
+ * in the specified TZDB timezone.  The match is not case-sensitive.
+ */
+static bool
+TimeZoneAbbrevIsKnown(const char *abbr, pg_tz *tzp)
+{
+	int			offset,
+				isdst;
+
+	/*
+	 * DetermineTimeZoneAbbrevOffsetInternal does more than is really needed
+	 * here, but it's not clear that it's worth optimizing further.
+	 *
+	 * We can use the epoch as the probe time, since we don't care here about
+	 * exactly what the abbreviation resolves as.
+	 */
+	return DetermineTimeZoneAbbrevOffsetInternal((pg_time_t) 0,
+												 abbr,
+												 tzp,
+												 &offset,
+												 &isdst);
+}
+
+
 /* DetermineTimeZoneAbbrevOffsetInternal()
  *
- * Workhorse for above two functions: work from a pg_time_t probe instant.
+ * Workhorse for above three functions: work from a pg_time_t probe instant.
  * On success, return GMT offset and DST status into *offset and *isdst.
  */
 static bool
@@ -3106,9 +3132,25 @@ DecodeTimezoneAbbrev(int field, const char *lowtoken,
 	}
 	if (tp == NULL)
 	{
-		*ftype = UNKNOWN_FIELD;
-		*offset = 0;
-		*tz = NULL;
+		/*
+		 * See if the current session_timezone recognizes it.  This is mainly
+		 * meant to handle "LMT", whose meaning varies across timezones, so we
+		 * don't try to cache the result.
+		 */
+		if (session_timezone &&
+			TimeZoneAbbrevIsKnown(lowtoken, session_timezone))
+		{
+			/* we can treat it like a dynamic-offset abbreviation */
+			*ftype = DYNTZ;
+			*offset = 0;
+			*tz = session_timezone;
+		}
+		else
+		{
+			*ftype = UNKNOWN_FIELD;
+			*offset = 0;
+			*tz = NULL;
+		}
 	}
 	else
 	{
@@ -3278,9 +3320,6 @@ DecodeTimezoneAbbrevPrefix(const char *str, int *offset, pg_tz **tz)
 	*offset = 0;				/* avoid uninitialized vars on failure */
 	*tz = NULL;
 
-	if (!zoneabbrevtbl)
-		return -1;				/* no abbrevs known, so fail immediately */
-
 	/* Downcase as much of the string as we could need */
 	for (len = 0; len < TOKMAXLEN; len++)
 	{
@@ -3299,9 +3338,12 @@ DecodeTimezoneAbbrevPrefix(const char *str, int *offset, pg_tz **tz)
 	 */
 	while (len > 0)
 	{
-		const datetkn *tp = datebsearch(lowtoken, zoneabbrevtbl->abbrevs,
-										zoneabbrevtbl->numabbrevs);
+		const datetkn *tp = NULL;
 
+		/* Known in zoneabbrevtbl? */
+		if (zoneabbrevtbl)
+			tp = datebsearch(lowtoken, zoneabbrevtbl->abbrevs,
+							 zoneabbrevtbl->numabbrevs);
 		if (tp != NULL)
 		{
 			if (tp->type == DYNTZ)
@@ -3324,6 +3366,17 @@ DecodeTimezoneAbbrevPrefix(const char *str, int *offset, pg_tz **tz)
 				return len;
 			}
 		}
+
+		/* See if the current session_timezone recognizes it. */
+		if (session_timezone &&
+			TimeZoneAbbrevIsKnown(lowtoken, session_timezone))
+		{
+			/* we can treat it like a dynamic-offset abbreviation */
+			*tz = session_timezone;
+			return len;
+		}
+
+		/* Nope, try the next shorter string. */
 		lowtoken[--len] = '\0';
 	}
 
diff --git a/src/test/regress/expected/horology.out b/src/test/regress/expected/horology.out
index cb28dfbaee..b90bfcd794 100644
--- a/src/test/regress/expected/horology.out
+++ b/src/test/regress/expected/horology.out
@@ -3332,6 +3332,12 @@ SELECT to_timestamp('2011-12-18 11:38 MSK', 'YYYY-MM-DD HH12:MI TZ');  -- dyntz
  Sat Dec 17 23:38:00 2011 PST
 (1 row)
 
+SELECT to_timestamp('2011-12-18 00:00 LMT', 'YYYY-MM-DD HH24:MI TZ');  -- dyntz
+         to_timestamp         
+------------------------------
+ Sat Dec 17 23:52:58 2011 PST
+(1 row)
+
 SELECT to_timestamp('2011-12-18 11:38ESTFOO24', 'YYYY-MM-DD HH12:MITZFOOSS');
          to_timestamp         
 ------------------------------
diff --git a/src/test/regress/expected/timestamptz.out b/src/test/regress/expected/timestamptz.out
index b437613ac8..b5f0e0b8db 100644
--- a/src/test/regress/expected/timestamptz.out
+++ b/src/test/regress/expected/timestamptz.out
@@ -176,6 +176,45 @@ SELECT '205000-01-10 17:32:01 Europe/Helsinki'::timestamptz; -- non-DST
  Fri Jan 10 07:32:01 205000 PST
 (1 row)
 
+-- Recognize "LMT" as whatever it means in the current zone
+SELECT 'Jan 01 00:00:00 1000'::timestamptz;
+         timestamptz          
+------------------------------
+ Wed Jan 01 00:00:00 1000 LMT
+(1 row)
+
+SELECT 'Jan 01 00:00:00 1000 LMT'::timestamptz;
+         timestamptz          
+------------------------------
+ Wed Jan 01 00:00:00 1000 LMT
+(1 row)
+
+SELECT 'Jan 01 00:00:00 2024 LMT'::timestamptz;
+         timestamptz          
+------------------------------
+ Sun Dec 31 23:52:58 2023 PST
+(1 row)
+
+SET timezone = 'Europe/London';
+SELECT 'Jan 01 00:00:00 1000 LMT'::timestamptz;
+         timestamptz          
+------------------------------
+ Wed Jan 01 00:00:00 1000 LMT
+(1 row)
+
+SELECT 'Jan 01 00:00:00 2024 LMT'::timestamptz;
+         timestamptz          
+------------------------------
+ Mon Jan 01 00:01:15 2024 GMT
+(1 row)
+
+-- which might be nothing
+SET timezone = 'UTC';
+SELECT 'Jan 01 00:00:00 2024 LMT'::timestamptz;  -- fail
+ERROR:  invalid input syntax for type timestamp with time zone: "Jan 01 00:00:00 2024 LMT"
+LINE 1: SELECT 'Jan 01 00:00:00 2024 LMT'::timestamptz;
+               ^
+RESET timezone;
 -- Test non-error-throwing API
 SELECT pg_input_is_valid('now', 'timestamptz');
  pg_input_is_valid 
diff --git a/src/test/regress/sql/horology.sql b/src/test/regress/sql/horology.sql
index 4aa88b4ba9..1310b43277 100644
--- a/src/test/regress/sql/horology.sql
+++ b/src/test/regress/sql/horology.sql
@@ -538,6 +538,7 @@ SELECT to_timestamp('2011-12-18 11:38 EST', 'YYYY-MM-DD HH12:MI TZ');
 SELECT to_timestamp('2011-12-18 11:38 -05', 'YYYY-MM-DD HH12:MI TZ');
 SELECT to_timestamp('2011-12-18 11:38 +01:30', 'YYYY-MM-DD HH12:MI TZ');
 SELECT to_timestamp('2011-12-18 11:38 MSK', 'YYYY-MM-DD HH12:MI TZ');  -- dyntz
+SELECT to_timestamp('2011-12-18 00:00 LMT', 'YYYY-MM-DD HH24:MI TZ');  -- dyntz
 SELECT to_timestamp('2011-12-18 11:38ESTFOO24', 'YYYY-MM-DD HH12:MITZFOOSS');
 SELECT to_timestamp('2011-12-18 11:38-05FOO24', 'YYYY-MM-DD HH12:MITZFOOSS');
 SELECT to_timestamp('2011-12-18 11:38 JUNK', 'YYYY-MM-DD HH12:MI TZ');  -- error
diff --git a/src/test/regress/sql/timestamptz.sql b/src/test/regress/sql/timestamptz.sql
index 6b91e7eddc..ea0ffca310 100644
--- a/src/test/regress/sql/timestamptz.sql
+++ b/src/test/regress/sql/timestamptz.sql
@@ -109,6 +109,18 @@ SELECT '20500110 173201 Europe/Helsinki'::timestamptz; -- non-DST
 SELECT '205000-07-10 17:32:01 Europe/Helsinki'::timestamptz; -- DST
 SELECT '205000-01-10 17:32:01 Europe/Helsinki'::timestamptz; -- non-DST
 
+-- Recognize "LMT" as whatever it means in the current zone
+SELECT 'Jan 01 00:00:00 1000'::timestamptz;
+SELECT 'Jan 01 00:00:00 1000 LMT'::timestamptz;
+SELECT 'Jan 01 00:00:00 2024 LMT'::timestamptz;
+SET timezone = 'Europe/London';
+SELECT 'Jan 01 00:00:00 1000 LMT'::timestamptz;
+SELECT 'Jan 01 00:00:00 2024 LMT'::timestamptz;
+-- which might be nothing
+SET timezone = 'UTC';
+SELECT 'Jan 01 00:00:00 2024 LMT'::timestamptz;  -- fail
+RESET timezone;
+
 -- Test non-error-throwing API
 SELECT pg_input_is_valid('now', 'timestamptz');
 SELECT pg_input_is_valid('garbage', 'timestamptz');