diff --git a/compiler-rt/test/lit.common.cfg.py b/compiler-rt/test/lit.common.cfg.py
--- a/compiler-rt/test/lit.common.cfg.py
+++ b/compiler-rt/test/lit.common.cfg.py
@@ -697,16 +697,16 @@
 
 if config.host_os == 'Darwin':
   config.substitutions.append((
-    "%get_pid_from_output", 
+    "%get_pid_from_output",
     "{} {}/get_pid_from_output.py".format(
-      sh_quote(config.python_executable), 
+      sh_quote(config.python_executable),
       sh_quote(get_ios_commands_dir())
     ))
   )
   config.substitutions.append(
-    ("%print_crashreport_for_pid", 
+    ("%print_crashreport_for_pid",
     "{} {}/print_crashreport_for_pid.py".format(
-      sh_quote(config.python_executable), 
+      sh_quote(config.python_executable),
       sh_quote(get_ios_commands_dir())
     ))
   )
diff --git a/compiler-rt/test/sanitizer_common/ios_commands/iossim_run.py b/compiler-rt/test/sanitizer_common/ios_commands/iossim_run.py
--- a/compiler-rt/test/sanitizer_common/ios_commands/iossim_run.py
+++ b/compiler-rt/test/sanitizer_common/ios_commands/iossim_run.py
@@ -4,6 +4,9 @@
 
 
 device_id = os.environ.get('SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER')
+iossim_run_verbose = os.environ.get('SANITIZER_IOSSIM_RUN_VERBOSE')
+wait_for_debug = os.environ.get('SANITIZER_IOSSIM_RUN_WAIT_FOR_DEBUGGER')
+
 if not device_id:
   raise EnvironmentError("Specify SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER to select which simulator to use.")
 
@@ -36,7 +39,18 @@
   # We use `shell=True` so that any wildcard globs get expanded by the shell.
   exitcode = subprocess.call(rm_cmd_line_str, shell=True)
 else:
-  exitcode = subprocess.call(["xcrun", "simctl", "spawn", "--standalone", device_id] + sys.argv[1:])
+  cmd = ["xcrun", "simctl", "spawn", "--standalone"]
+
+  if wait_for_debug:
+    cmd.append("--wait-for-debugger")
+
+  cmd.append(device_id)
+  cmd += sys.argv[1:]
+
+  if iossim_run_verbose:
+    print("RUNNING: \t{}".format(" ".join(cmd)))
+
+  exitcode = subprocess.call(cmd)
 if exitcode > 125:
   exitcode = 126
 sys.exit(exitcode)