diff --git a/CHANGES b/CHANGES
index f2fa4f4fbe..7ef9c6af45 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,9 @@
+4380.	[experimental]	Added a "zone-directory" option to "catalog-zones"
+			syntax, allowing local masterfiles for slaves
+			that are provisioned by catalog zones to be stored
+			in a directory other than the server's working
+			directory. [RT #42527]
+
 4379.   [bug]           An INSIST could be triggered if a zone contains
 			RRSIG records with expiry fields that loop
 			using serial number arithmetic. [RT #40571]
diff --git a/bin/named/server.c b/bin/named/server.c
index 58ab7c06be..cd9ed0d17c 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -2367,6 +2367,11 @@ configure_catz_zone(dns_view_t *view, const cfg_obj_t *config,
 		result = ns_config_getipandkeylist(config, obj,
 						   view->mctx, &opts->masters);
 
+	obj = cfg_tuple_get(catz_obj, "zone-directory");
+	if (obj != NULL)
+		opts->zonedir = isc_mem_strdup(view->mctx,
+					       cfg_obj_asstring(obj));
+
 	obj = cfg_tuple_get(catz_obj, "in-memory");
 	if (obj != NULL && cfg_obj_isboolean(obj))
 		opts->in_memory = cfg_obj_asboolean(obj);
diff --git a/bin/tests/system/catz/clean.sh b/bin/tests/system/catz/clean.sh
index bf1b2d5aa9..9912e55dcd 100644
--- a/bin/tests/system/catz/clean.sh
+++ b/bin/tests/system/catz/clean.sh
@@ -17,7 +17,8 @@ rm -f nsupdate.out.*
 rm -f ns*/named.memstats
 rm -f ns*/named.run
 rm -f ns*/named.lock
-rm -f ns{1,2}/*dom*example.db
+rm -f ns1/*dom*example.db
 rm -f ns{1,2}/catalog.example.db
+rm -rf ns2/zonedir
 rm -f ns*/*.jnl
 rm -f ns*/*.nzf
diff --git a/bin/tests/system/catz/ns2/named.conf b/bin/tests/system/catz/ns2/named.conf
index 4cd508d78b..a641a5c160 100644
--- a/bin/tests/system/catz/ns2/named.conf
+++ b/bin/tests/system/catz/ns2/named.conf
@@ -32,7 +32,10 @@ options {
 	recursion no;
 	serial-query-rate 100;
 	catalog-zones {
-		zone "catalog.example" default-masters { 10.53.0.1; };
+		zone "catalog.example"
+                        default-masters { 10.53.0.1; }
+                        in-memory no
+                        zone-directory "zonedir";
 	};
 };
 
diff --git a/bin/tests/system/catz/setup.sh b/bin/tests/system/catz/setup.sh
index 8e0d3e8d86..7a3dbcdb7d 100644
--- a/bin/tests/system/catz/setup.sh
+++ b/bin/tests/system/catz/setup.sh
@@ -20,3 +20,4 @@ SYSTEMTESTTOP=..
 $SHELL clean.sh
 
 cat ns1/catalog.example.db.in > ns1/catalog.example.db
+mkdir ns2/zonedir
diff --git a/bin/tests/system/catz/tests.sh b/bin/tests/system/catz/tests.sh
index c72b99c690..4546d89ef3 100644
--- a/bin/tests/system/catz/tests.sh
+++ b/bin/tests/system/catz/tests.sh
@@ -301,5 +301,13 @@ grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 if [ $ret != 0 ]; then echo "I:failed"; fi
 status=`expr $status + $ret`
 
+n=`expr $n + 1`
+echo "I:checking that zone-directory is populated ($n)"
+ret=0
+[ -f "ns2/zonedir/__catz___default_catalog.example_dom3.example.db" ] || ret=1
+[ -f "ns2/zonedir/__catz___default_catalog.example_dom4.example.db" ] || ret=1
+if [ $ret != 0 ]; then echo "I:failed"; fi
+status=`expr $status + $ret`
+
 echo "I:exit status: $status"
 exit $status
diff --git a/doc/arm/catz.xml b/doc/arm/catz.xml
index 87cf5fbaec..6f19f90eb2 100644
--- a/doc/arm/catz.xml
+++ b/doc/arm/catz.xml
@@ -110,7 +110,11 @@
     </para>
 <screen>
 catalog-zones {
-    zone "catalog.example" default-masters { 10.53.0.1; } in-memory true min-update-interval 10;
+	zone "catalog.example"
+	     default-masters { 10.53.0.1; } 
+	     in-memory no
+	     zone-directory "catzones"
+	     min-update-interval 10;
 };
 </screen>
     <para>
@@ -119,6 +123,10 @@ catalog-zones {
       properly configured in the same view. In most configurations, it would
       be a slave zone.
     </para>
+    <para>
+      The options following the zone name are not required, and may be
+      specified in any order:
+    </para>
     <para>
       The <option>default-masters</option> option defines the default masters
       for member zones listed in a catalog zone. This can be overridden by
@@ -134,6 +142,14 @@ catalog-zones {
       will be stored locally in a file whose name is automatically generated
       from the view name, catalog zone name, and member zone name.
     </para>
+    <para>
+      The <option>zone-directory</option> option causes local copies of
+      member zones' master files (if <option>in-memory</option> is not set
+      to <literal>yes</literal>) to be stored in the specified directory.
+      The default is to store zone files in the server's working directory.
+      A non-absolute pathname in <option>zone-directory</option> is
+      assumed to be relative to the working directory.
+    </para>
     <para>
       The <option>min-update-interval</option> option sets the minimum
       interval between processing of updates to catalog zones, in seconds.
diff --git a/lib/dns/catz.c b/lib/dns/catz.c
index 46b467962e..9364ff1fc0 100644
--- a/lib/dns/catz.c
+++ b/lib/dns/catz.c
@@ -96,12 +96,17 @@ dns_catz_options_init(dns_catz_options_t *options) {
 
 	options->in_memory = ISC_FALSE;
 	options->min_update_interval = 5;
+	options->zonedir = NULL;
 }
 
 void
 dns_catz_options_free(dns_catz_options_t *options, isc_mem_t *mctx) {
 	if (options->masters.count > 0)
 		dns_ipkeylist_clear(mctx, &options->masters);
+	if (options->zonedir != NULL) {
+		isc_mem_free(mctx, options->zonedir);
+		options->zonedir = NULL;
+	}
 }
 
 isc_result_t
@@ -112,10 +117,17 @@ dns_catz_options_copy(isc_mem_t *mctx, const dns_catz_options_t *src,
 	REQUIRE(dst != NULL);
 	REQUIRE(dst->masters.count == 0);
 
-	if (src->masters.count != 0) {
+	if (src->masters.count != 0)
 		dns_ipkeylist_copy(mctx, &src->masters, &dst->masters);
+
+	if (dst->zonedir != NULL) {
+		isc_mem_free(mctx, dst->zonedir);
+		dst->zonedir = NULL;
 	}
 
+	if (src->zonedir != NULL)
+		dst->zonedir = isc_mem_strdup(mctx, src->zonedir);
+
 	return (ISC_R_SUCCESS);
 }
 
@@ -125,6 +137,8 @@ dns_catz_options_setdefault(isc_mem_t *mctx, const dns_catz_options_t *defaults,
 {
 	if (opts->masters.count == 0)
 		dns_catz_options_copy(mctx, defaults, opts);
+	else if (defaults->zonedir != NULL)
+		opts->zonedir = isc_mem_strdup(mctx, defaults->zonedir);
 
 	/* This option is always taken from config, so it's always 'default' */
 	opts->in_memory = defaults->in_memory;
@@ -234,7 +248,6 @@ dns_catz_entry_cmp(const dns_catz_entry_t *ea, const dns_catz_entry_t *eb) {
 	return (ISC_TRUE);
 }
 
-
 dns_name_t *
 dns_catz_zone_getname(dns_catz_zone_t *zone) {
 	REQUIRE(zone != NULL);
@@ -1072,6 +1085,7 @@ dns_catz_generate_masterfilename(dns_catz_zone_t *zone, dns_catz_entry_t *entry,
 	isc_sha256_t sha256;
 	isc_region_t r;
 	isc_result_t result;
+	size_t rlen;
 
 	REQUIRE(zone != NULL);
 	REQUIRE(entry != NULL);
@@ -1079,26 +1093,38 @@ dns_catz_generate_masterfilename(dns_catz_zone_t *zone, dns_catz_entry_t *entry,
 
 	result = isc_buffer_allocate(zone->catzs->mctx, &tbuf,
 				     strlen(zone->catzs->view->name) +
-				     2*DNS_NAME_FORMATSIZE + 2);
+				     2 * DNS_NAME_FORMATSIZE + 2);
 	if (result != ISC_R_SUCCESS)
 		return (result);
 	INSIST(tbuf != NULL);
+
 	isc_buffer_putstr(tbuf, zone->catzs->view->name);
 	isc_buffer_putstr(tbuf, "_");
 	result = dns_name_totext(&zone->name, ISC_TRUE, tbuf);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup;
+
 	isc_buffer_putstr(tbuf, "_");
 	result = dns_name_totext(&entry->name, ISC_TRUE, tbuf);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup;
 
-	result = isc_buffer_reserve(buffer, strlen("__catz__") +
-				    ISC_SHA256_DIGESTSTRINGLENGTH +
-				    strlen(".db"));
+	/* __catz__<digest>.db */
+	rlen = ISC_SHA256_DIGESTSTRINGLENGTH + 12;
+
+	/* optionally prepend with <zonedir>/ */
+	if (entry->opts.zonedir != NULL)
+		rlen += strlen(entry->opts.zonedir) + 1;
+
+	result = isc_buffer_reserve(buffer, rlen);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup;
 
+	if (entry->opts.zonedir != NULL) {
+		isc_buffer_putstr(*buffer, entry->opts.zonedir);
+		isc_buffer_putstr(*buffer, "/");
+	}
+
 	isc_buffer_usedregion(tbuf, &r);
 	isc_buffer_putstr(*buffer, "__catz__");
 	if (tbuf->used > ISC_SHA256_DIGESTSTRINGLENGTH) {
@@ -1110,11 +1136,13 @@ dns_catz_generate_masterfilename(dns_catz_zone_t *zone, dns_catz_entry_t *entry,
 	} else {
 		isc_buffer_copyregion(*buffer, &r);
 	}
+
 	isc_buffer_putstr(*buffer, ".db");
 	result = ISC_R_SUCCESS;
 
 cleanup:
-	isc_buffer_free(&tbuf);
+	if (tbuf != NULL)
+		isc_buffer_free(&tbuf);
 	return (result);
 }
 
diff --git a/lib/dns/include/dns/catz.h b/lib/dns/include/dns/catz.h
index 7cff8b9b33..73bd25028e 100644
--- a/lib/dns/include/dns/catz.h
+++ b/lib/dns/include/dns/catz.h
@@ -51,12 +51,15 @@ struct dns_catz_entry_options {
 	/*
 	 * Options that can be overriden in catalog zone
 	 */
-	/* masters definition */
+	/* default-masters definition */
 	dns_ipkeylist_t masters;
 
 	/*
 	 * Options that are only set in named.conf
 	 */
+	/* zone-directory definition */
+	char *zonedir;
+
 	/* zone should not be stored on disk (no 'file' statement in def */
 	isc_boolean_t in_memory;
 	/*
diff --git a/lib/isccfg/namedconf.c b/lib/isccfg/namedconf.c
index a3ca7c8163..f45eec6483 100644
--- a/lib/isccfg/namedconf.c
+++ b/lib/isccfg/namedconf.c
@@ -1484,6 +1484,7 @@ static cfg_type_t cfg_type_catz_zone = {
 static cfg_tuplefielddef_t catz_zone_fields[] = {
 	{ "zone name", &cfg_type_catz_zone, 0 },
 	{ "default-masters", &cfg_type_namesockaddrkeylist, 0 },
+	{ "zone-directory", &cfg_type_qstring, 0 },
 	{ "in-memory", &cfg_type_boolean, 0 },
 	{ "min-update-interval", &cfg_type_uint32, 0 },
 	{ NULL, NULL, 0 }