diff --git a/doc/configuration.txt b/doc/configuration.txt
index babcefcafe..bc582c29e0 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -2578,7 +2578,9 @@ fullconn <conns>
 
   Since it's hard to get this value right, haproxy automatically sets it to
   10% of the sum of the maxconns of all frontends that may branch to this
-  backend. That way it's safe to leave it unset.
+  backend (based on "use_backend" and "default_backend" rules). That way it's
+  safe to leave it unset. However, "use_backend" involving dynamic names are
+  not counted since there is no way to know if they could match or not.
 
   Example :
      # The servers will accept between 100 and 1000 concurrent connections each
@@ -7711,7 +7713,8 @@ use_backend <backend> unless <condition>
   May be used in sections :   defaults | frontend | listen | backend
                                   no   |    yes   |   yes  |   no
   Arguments :
-    <backend>   is the name of a valid backend or "listen" section.
+    <backend>   is the name of a valid backend or "listen" section, or a
+                "log-format" string resolving to a backend name.
 
     <condition> is a condition composed of ACLs, as described in section 7.
 
@@ -7740,7 +7743,22 @@ use_backend <backend> unless <condition>
   a complete HTTP request to get in. This feature is useful when a frontend
   must decode several protocols on a unique port, one of them being HTTP.
 
-  See also: "default_backend", "tcp-request", and section 7 about ACLs.
+  When <backend> is a simple name, it is resolved at configuration time, and an
+  error is reported if the specified backend does not exist. If <backend> is
+  a log-format string instead, no check may be done at configuration time, so
+  the backend name is resolved dynamically at run time. If the resulting
+  backend name does not correspond to any valid backend, no other rule is
+  evaluated, and the default_backend directive is applied instead. Note that
+  when using dynamic backend names, it is highly recommended to use a prefix
+  that no other backend uses in order to ensure that an unauthorized backend
+  cannot be forced from the request.
+
+  It is worth mentionning that "use_backend" rules with an explicit name are
+  used to detect the association between frontends and backends to compute the
+  backend's "fullconn" setting. This cannot be done for dynamic names.
+
+  See also: "default_backend", "tcp-request", "fullconn", "log-format", and
+            section 7 about ACLs.
 
 
 use-server <server> if <condition>
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 1a778bd911..dc75f63dbd 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -379,9 +379,11 @@ struct proxy {
 struct switching_rule {
 	struct list list;			/* list linked to from the proxy */
 	struct acl_cond *cond;			/* acl condition to meet */
+	int dynamic;				/* this is a dynamic rule using the logformat expression */
 	union {
 		struct proxy *backend;		/* target backend */
 		char *name;			/* target backend name during config parsing */
+		struct list expr;		/* logformat expression to use for dynamic rules */
 	} be;
 };
 
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 9f91f2813a..e433c2c275 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -6813,6 +6813,33 @@ int check_config_validity()
 		/* find the target proxy for 'use_backend' rules */
 		list_for_each_entry(rule, &curproxy->switching_rules, list) {
 			struct proxy *target;
+			struct logformat_node *node;
+			char *pxname;
+
+			/* Try to parse the string as a log format expression. If the result
+			 * of the parsing is only one entry containing a simple string, then
+			 * it's a standard string corresponding to a static rule, thus the
+			 * parsing is cancelled and be.name is restored to be resolved.
+			 */
+			pxname = rule->be.name;
+			LIST_INIT(&rule->be.expr);
+			parse_logformat_string(pxname, curproxy, &rule->be.expr, 0, SMP_VAL_FE_HRQ_HDR,
+			                       curproxy->conf.args.file, curproxy->conf.args.line);
+			node = LIST_NEXT(&rule->be.expr, struct logformat_node *, list);
+
+			if (!LIST_ISEMPTY(&rule->be.expr)) {
+				if (node->type != LOG_FMT_TEXT || node->list.n != &rule->be.expr) {
+					rule->dynamic = 1;
+					free(pxname);
+					continue;
+				}
+				/* simple string: free the expression and fall back to static rule */
+				free(node->arg);
+				free(node);
+			}
+
+			rule->dynamic = 0;
+			rule->be.name = pxname;
 
 			target = findproxy_mode(rule->be.name, curproxy->mode, PR_CAP_BE);
 
@@ -7722,7 +7749,7 @@ int check_config_validity()
 				/* check if a "use_backend" rule matches */
 				if (!found) {
 					list_for_each_entry(rule, &fe->switching_rules, list) {
-						if (rule->be.backend == curproxy) {
+						if (!rule->dynamic && rule->be.backend == curproxy) {
 							found = 1;
 							break;
 						}
diff --git a/src/session.c b/src/session.c
index a8f68a29c3..efc0736ec0 100644
--- a/src/session.c
+++ b/src/session.c
@@ -1244,7 +1244,24 @@ static int process_switching_rules(struct session *s, struct channel *req, int a
 				ret = !ret;
 
 			if (ret) {
-				if (!session_set_backend(s, rule->be.backend))
+				/* If the backend name is dynamic, try to resolve the name.
+				 * If we can't resolve the name, or if any error occurs, break
+				 * the loop and fallback to the default backend.
+				 */
+				struct proxy *backend;
+
+				if (rule->dynamic) {
+					struct chunk *tmp = get_trash_chunk();
+					if (!build_logline(s, tmp->str, tmp->size, &rule->be.expr))
+						break;
+					backend = findproxy(tmp->str, PR_CAP_BE);
+					if (!backend)
+						break;
+				}
+				else
+					backend = rule->be.backend;
+
+				if (!session_set_backend(s, backend))
 					goto sw_failed;
 				break;
 			}