diff --git a/tools/perf/Documentation/itrace.txt b/tools/perf/Documentation/itrace.txt
index 671e154..0326050 100644
--- a/tools/perf/Documentation/itrace.txt
+++ b/tools/perf/Documentation/itrace.txt
@@ -12,6 +12,7 @@
 		g	synthesize a call chain (use with i or x)
 		G	synthesize a call chain on existing event records
 		l	synthesize last branch entries (use with i or x)
+		L	synthesize last branch entries on existing event records
 		s       skip initial number of events
 
 	The default is all events i.e. the same as --itrace=ibxwpe,
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 7e124a7..7c4403c 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -684,7 +684,8 @@ static int __cmd_inject(struct perf_inject *inject)
 
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
-			if (inject->itrace_synth_opts.last_branch)
+			if (inject->itrace_synth_opts.last_branch ||
+			    inject->itrace_synth_opts.add_last_branch)
 				perf_header__set_feat(&session->header,
 						      HEADER_BRANCH_STACK);
 			evsel = perf_evlist__id2evsel_strict(session->evlist,
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 7da1342..0eea667 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -349,7 +349,8 @@ static int report__setup_sample_type(struct report *rep)
 	     !session->itrace_synth_opts->set))
 		sample_type |= PERF_SAMPLE_CALLCHAIN;
 
-	if (session->itrace_synth_opts->last_branch)
+	if (session->itrace_synth_opts->last_branch ||
+	    session->itrace_synth_opts->add_last_branch)
 		sample_type |= PERF_SAMPLE_BRANCH_STACK;
 
 	if (!is_pipe && !(sample_type & PERF_SAMPLE_CALLCHAIN)) {
@@ -1393,7 +1394,7 @@ int cmd_report(int argc, const char **argv)
 		goto error;
 	}
 
-	if (itrace_synth_opts.last_branch)
+	if (itrace_synth_opts.last_branch || itrace_synth_opts.add_last_branch)
 		has_br_stack = true;
 
 	if (has_br_stack && branch_call_mode)
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index ac6e099..83ea7ca 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -1464,8 +1464,12 @@ int itrace_parse_synth_opts(const struct option *opt, const char *str,
 				synth_opts->callchain_sz = val;
 			}
 			break;
+		case 'L':
 		case 'l':
-			synth_opts->last_branch = true;
+			if (p[-1] == 'L')
+				synth_opts->add_last_branch = true;
+			else
+				synth_opts->last_branch = true;
 			synth_opts->last_branch_sz =
 					PERF_ITRACE_DEFAULT_LAST_BRANCH_SZ;
 			while (*p == ' ' || *p == ',')
diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index dd8a4ff..0220a2e 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -77,6 +77,7 @@ enum itrace_period_type {
  * @add_callchain: add callchain to existing event records
  * @thread_stack: feed branches to the thread_stack
  * @last_branch: add branch context to 'instruction' events
+ * @add_last_branch: add branch context to existing event records
  * @callchain_sz: maximum callchain size
  * @last_branch_sz: branch context size
  * @period: 'instructions' events period
@@ -105,6 +106,7 @@ struct itrace_synth_opts {
 	bool			add_callchain;
 	bool			thread_stack;
 	bool			last_branch;
+	bool			add_last_branch;
 	unsigned int		callchain_sz;
 	unsigned int		last_branch_sz;
 	unsigned long long	period;
diff --git a/tools/perf/util/s390-cpumsf.c b/tools/perf/util/s390-cpumsf.c
index 38a9428..f886199 100644
--- a/tools/perf/util/s390-cpumsf.c
+++ b/tools/perf/util/s390-cpumsf.c
@@ -1079,7 +1079,8 @@ static bool check_auxtrace_itrace(struct itrace_synth_opts *itops)
 		itops->pwr_events || itops->errors ||
 		itops->dont_decode || itops->calls || itops->returns ||
 		itops->callchain || itops->thread_stack ||
-		itops->last_branch || itops->add_callchain;
+		itops->last_branch || itops->add_callchain ||
+		itops->add_last_branch;
 	if (!ison)
 		return true;
 	pr_err("Unsupported --itrace options specified\n");