diff --git a/src/RunState.cc b/src/RunState.cc
index 7c24ee18c4..5e44eb8129 100644
--- a/src/RunState.cc
+++ b/src/RunState.cc
@@ -63,6 +63,7 @@ double current_wallclock = 0.0;
 double current_pseudo = 0.0;
 bool zeek_init_done = false;
 bool time_updated = false;
+bool bare_mode = false;
 
 RETSIGTYPE watchdog(int /* signo */)
 	{
diff --git a/src/RunState.h b/src/RunState.h
index 3b9171c483..d3ba66c8a3 100644
--- a/src/RunState.h
+++ b/src/RunState.h
@@ -65,6 +65,8 @@ extern double current_pseudo;
 
 extern bool zeek_init_done;
 
+extern bool bare_mode; // True if Zeek was started in bare mode.
+
 	} // namespace detail
 
 // Functions to temporarily suspend processing of live input (network packets
diff --git a/src/zeek-setup.cc b/src/zeek-setup.cc
index f682d39118..df8294816d 100644
--- a/src/zeek-setup.cc
+++ b/src/zeek-setup.cc
@@ -516,6 +516,8 @@ SetupResult setup(int argc, char** argv, Options* zopts)
 
 	auto options = zopts ? *zopts : parse_cmdline(argc, argv);
 
+	run_state::detail::bare_mode = options.bare_mode;
+
 	// Set up the global that facilitates access to analysis/optimization
 	// options from deep within some modules.
 	analysis_options = options.analysis_options;
diff --git a/src/zeek.bif b/src/zeek.bif
index a1fc14b26c..39a73af809 100644
--- a/src/zeek.bif
+++ b/src/zeek.bif
@@ -1748,6 +1748,20 @@ function zeek_version%(%): string
 	return zeek::make_intrusive<zeek::StringVal>(zeek::zeek_version());
 	%}
 
+%%{
+namespace zeek::run_state::detail {
+extern bool bare_mode;
+} // namespace zeek::run_state::detail
+%%}
+
+## Returns whether Zeek was started in bare mode.
+##
+## Returns: True if Zeek was started in bare mode, false otherwise.
+function bare_mode%(%): bool
+	%{
+	return zeek::val_mgr->Bool(zeek::run_state::detail::bare_mode);
+	%}
+
 ## Converts a record type name to a vector of strings, where each element is
 ## the name of a record field. Nested records are flattened.
 ##
diff --git a/testing/btest/Baseline/bifs.bare_mode/output b/testing/btest/Baseline/bifs.bare_mode/output
new file mode 100644
index 0000000000..1956db8698
--- /dev/null
+++ b/testing/btest/Baseline/bifs.bare_mode/output
@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+F
+T
diff --git a/testing/btest/bifs/bare_mode.zeek b/testing/btest/bifs/bare_mode.zeek
new file mode 100644
index 0000000000..5183cde7d3
--- /dev/null
+++ b/testing/btest/bifs/bare_mode.zeek
@@ -0,0 +1,8 @@
+# @TEST-EXEC: zeek %INPUT >>output
+# @TEST-EXEC: zeek -b %INPUT >>output
+# @TEST-EXEC: btest-diff output
+
+event zeek_init()
+	{
+	print bare_mode();
+	}