diff --git a/candm.h b/candm.h
index 52edf29..fe4d5b4 100644
--- a/candm.h
+++ b/candm.h
@@ -269,6 +269,7 @@ typedef struct {
 #define REQ_ADDSRC_INTERLEAVED 0x80
 #define REQ_ADDSRC_BURST 0x100
 #define REQ_ADDSRC_NTS 0x200
+#define REQ_ADDSRC_COPY 0x400
 
 typedef struct {
   uint32_t type;
diff --git a/client.c b/client.c
index c0e9022..17e4577 100644
--- a/client.c
+++ b/client.c
@@ -1098,6 +1098,7 @@ process_cmd_add_source(CMD_Request *msg, char *line)
           (data.params.interleaved ? REQ_ADDSRC_INTERLEAVED : 0) |
           (data.params.burst ? REQ_ADDSRC_BURST : 0) |
           (data.params.nts ? REQ_ADDSRC_NTS : 0) |
+          (data.params.copy ? REQ_ADDSRC_COPY : 0) |
           (data.params.sel_options & SRC_SELECT_PREFER ? REQ_ADDSRC_PREFER : 0) |
           (data.params.sel_options & SRC_SELECT_NOSELECT ? REQ_ADDSRC_NOSELECT : 0) |
           (data.params.sel_options & SRC_SELECT_TRUST ? REQ_ADDSRC_TRUST : 0) |
diff --git a/cmdmon.c b/cmdmon.c
index 3d17cb7..7ee8c12 100644
--- a/cmdmon.c
+++ b/cmdmon.c
@@ -767,6 +767,7 @@ handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
   params.interleaved = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_INTERLEAVED ? 1 : 0;
   params.burst = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_BURST ? 1 : 0;
   params.nts = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_NTS ? 1 : 0;
+  params.copy = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_COPY ? 1 : 0;
   params.sel_options =
     (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_PREFER ? SRC_SELECT_PREFER : 0) |
     (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_NOSELECT ? SRC_SELECT_NOSELECT : 0) |
diff --git a/cmdparse.c b/cmdparse.c
index 95d8953..e2c5115 100644
--- a/cmdparse.c
+++ b/cmdparse.c
@@ -64,6 +64,7 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
   src->params.sel_options = 0;
   src->params.nts = 0;
   src->params.nts_port = SRC_DEFAULT_NTSPORT;
+  src->params.copy = 0;
   src->params.authkey = INACTIVE_AUTHKEY;
   src->params.cert_set = SRC_DEFAULT_CERTSET;
   src->params.max_delay = SRC_DEFAULT_MAXDELAY;
@@ -91,6 +92,8 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
       src->params.auto_offline = 1;
     } else if (!strcasecmp(cmd, "burst")) {
       src->params.burst = 1;
+    } else if (!strcasecmp(cmd, "copy")) {
+      src->params.copy = 1;
     } else if (!strcasecmp(cmd, "iburst")) {
       src->params.iburst = 1;
     } else if (!strcasecmp(cmd, "offline")) {
diff --git a/doc/chrony.conf.adoc b/doc/chrony.conf.adoc
index 280278f..ff95ccc 100644
--- a/doc/chrony.conf.adoc
+++ b/doc/chrony.conf.adoc
@@ -278,6 +278,15 @@ specified by the *key* option and which authentication hash function the key
 is using. If the output size of the hash function is longer than 160 bits, the
 default version is 3 for compatibility with older *chronyd* servers. Otherwise,
 the default version is 4.
+*copy*:::
+This option specifies that the server and client are closely related, their
+configuration does not allow a synchronisation loop to form between them, and
+the client is allowed to assume the reference ID and stratum of the server.
+This is useful when multiple instances of `chronyd` are running on one computer
+(e.g. for security or performance reasons), one primarily operating as a client
+to synchronise the system clock and other instances started with the *-x*
+option to operate as NTP servers for other computers with their NTP clocks
+synchronised to the first instance.
 
 [[pool]]*pool* _name_ [_option_]...::
 The syntax of this directive is similar to that for the <<server,*server*>>
@@ -320,7 +329,7 @@ address of this host. *chronyd* does not support ephemeral associations.
 This directive can be used multiple times to specify multiple peers.
 +
 The following options of the *server* directive do not work in the *peer*
-directive: *iburst*, *burst*, *nts*, *presend*.
+directive: *iburst*, *burst*, *nts*, *presend*, *copy*.
 +
 When using the *xleave* option, both peers must support and have enabled the
 interleaved mode, otherwise the synchronisation will work in one direction
diff --git a/ntp_core.c b/ntp_core.c
index 51c11fd..5470022 100644
--- a/ntp_core.c
+++ b/ntp_core.c
@@ -107,6 +107,8 @@ struct NCR_Instance_Record {
   int min_stratum;              /* Increase stratum in received packets to the
                                    minimum */
 
+  int copy;                     /* Boolean suppressing own refid and stratum */
+
   int poll_target;              /* Target number of sourcestats samples */
 
   int version;                  /* Version set in packets for server/peer */
@@ -560,6 +562,7 @@ NCR_CreateInstance(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
   result->auto_iburst = params->iburst;
   result->auto_burst = params->burst;
   result->auto_offline = params->auto_offline;
+  result->copy = params->copy && result->mode == MODE_CLIENT;
   result->poll_target = params->poll_target;
 
   if (params->nts) {
@@ -1766,8 +1769,16 @@ process_response(NCR_Instance inst, NTP_Local_Address *local_addr,
     inst->tx_count = 0;
 
     SRC_UpdateReachability(inst->source, synced_packet);
-    if (synced_packet)
-      SRC_UpdateStatus(inst->source, MAX(message->stratum, inst->min_stratum), pkt_leap);
+
+    if (synced_packet) {
+      if (inst->copy && inst->remote_stratum > 0) {
+        /* Assume the reference ID and stratum of the server */
+        inst->remote_stratum--;
+        SRC_SetRefid(inst->source, ntohl(message->reference_id), &inst->remote_addr.ip_addr);
+      }
+
+      SRC_UpdateStatus(inst->source, MAX(inst->remote_stratum, inst->min_stratum), pkt_leap);
+    }
 
     if (good_packet) {
       /* Adjust the polling interval, accumulate the sample, etc. */
diff --git a/srcparams.h b/srcparams.h
index 81ad889..6211ec7 100644
--- a/srcparams.h
+++ b/srcparams.h
@@ -54,6 +54,7 @@ typedef struct {
   int sel_options;
   int nts;
   int nts_port;
+  int copy;
   uint32_t authkey;
   uint32_t cert_set;
   double max_delay;
diff --git a/test/simulation/141-copy b/test/simulation/141-copy
new file mode 100755
index 0000000..80e56bc
--- /dev/null
+++ b/test/simulation/141-copy
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "copy option"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+client_server_options="copy"
+chronyc_conf="tracking"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+check_chronyc_output "^Reference ID *: 7F7F0101 \(192\.168\.123\.1\)
+Stratum *: 1" || test_fail
+
+test_pass