diff --git a/interface-definitions/policy.xml.in b/interface-definitions/policy.xml.in
index c470cfdb3b..0d2ed97463 100644
--- a/interface-definitions/policy.xml.in
+++ b/interface-definitions/policy.xml.in
@@ -1446,9 +1446,18 @@
                         <format>u32:0-4294967295</format>
                         <description>Metric value</description>
                       </valueHelp>
+                      <valueHelp>
+                        <format>&lt;+/-rtt&gt;</format>
+                        <description>Add or subtract round trip time</description>
+                      </valueHelp>
+                      <valueHelp>
+                        <format>&lt;rtt&gt;</format>
+                        <description>Round trip time</description>
+                      </valueHelp>
                       <constraint>
                         <validator name="numeric" argument="--relative --"/>
                         <validator name="numeric" argument="--range 0-4294967295"/>
+                        <regex>^[+|-]?rtt$</regex>
                       </constraint>
                     </properties>
                   </leafNode>
diff --git a/smoketest/scripts/cli/test_policy.py b/smoketest/scripts/cli/test_policy.py
index 51a33f9787..c21d8af4e1 100755
--- a/smoketest/scripts/cli/test_policy.py
+++ b/smoketest/scripts/cli/test_policy.py
@@ -1107,6 +1107,33 @@ def test_route_map(self):
                             'metric' : '-20',
                         },
                     },
+                    '30': {
+                        'action': 'permit',
+                        'match': {
+                            'ip-nexthop-addr': ipv4_nexthop_address,
+                        },
+                        'set': {
+                            'metric': 'rtt',
+                        },
+                    },
+                    '40': {
+                        'action': 'permit',
+                        'match': {
+                            'ip-nexthop-addr': ipv4_nexthop_address,
+                        },
+                        'set': {
+                            'metric': '+rtt',
+                        },
+                    },
+                    '50': {
+                        'action': 'permit',
+                        'match': {
+                            'ip-nexthop-addr': ipv4_nexthop_address,
+                        },
+                        'set': {
+                            'metric': '-rtt',
+                        },
+                    },
                 },
             },
         }