diff --git a/layout/tools/reftest/mach_commands.py b/layout/tools/reftest/mach_commands.py
index f2f9c7ecd19a..b66e6a927a37 100644
--- a/layout/tools/reftest/mach_commands.py
+++ b/layout/tools/reftest/mach_commands.py
@@ -79,6 +79,7 @@ class ReftestRunner(MozbuildObject):
         args.extraProfileFiles.append(os.path.join(self.topobjdir, "dist", "plugins"))
         args.symbolsPath = os.path.join(self.topobjdir, "crashreporter-symbols")
         args.workPath = self.topsrcdir
+        args.objPath = self.topobjdir
 
         if not args.tests:
             args.tests = [os.path.join(*default_manifest[args.suite])]
diff --git a/layout/tools/reftest/reftestcommandline.py b/layout/tools/reftest/reftestcommandline.py
index c2b33bf49019..48f6e935c0f6 100644
--- a/layout/tools/reftest/reftestcommandline.py
+++ b/layout/tools/reftest/reftestcommandline.py
@@ -244,7 +244,12 @@ class ReftestArgumentsParser(argparse.ArgumentParser):
         self.add_argument("--work-path",
                           action="store",
                           dest="workPath",
-                          help="Path to the base dir of all test files.")
+                          help="Path to the base dir of all source files.")
+
+        self.add_argument("--obj-path",
+                          action="store",
+                          dest="objPath",
+                          help="Path to the base dir of all object files.")
 
         mozlog.commandline.add_logging_group(self)
 
diff --git a/layout/tools/reftest/runreftest.py b/layout/tools/reftest/runreftest.py
index aead256008d2..2eda417be40b 100644
--- a/layout/tools/reftest/runreftest.py
+++ b/layout/tools/reftest/runreftest.py
@@ -310,6 +310,11 @@ class RefTest(object):
                 sandbox_whitelist_paths.append(options.workPath)
         except AttributeError:
             pass
+        try:
+            if options.objPath:
+                sandbox_whitelist_paths.append(options.objPath)
+        except AttributeError:
+            pass
         if (platform.system() == "Linux" or
             platform.system() in ("Windows", "Microsoft")):
             # Trailing slashes are needed to indicate directories on Linux and Windows
diff --git a/testing/mochitest/mochitest_options.py b/testing/mochitest/mochitest_options.py
index 74c6b00c3843..cf437ab025a2 100644
--- a/testing/mochitest/mochitest_options.py
+++ b/testing/mochitest/mochitest_options.py
@@ -604,7 +604,13 @@ class MochitestArguments(ArgumentContainer):
         [["--work-path"],
          {"default": None,
           "dest": "workPath",
-          "help": "Path to the base dir of all test files.",
+          "help": "Path to the base dir of all source files.",
+          "suppress": True,
+          }],
+        [["--obj-path"],
+         {"default": None,
+          "dest": "objPath",
+          "help": "Path to the base dir of all object files.",
           "suppress": True,
           }],
         [["--verify"],
diff --git a/testing/mochitest/runtests.py b/testing/mochitest/runtests.py
index 942c12e1e038..1b1faf0d8d63 100644
--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -1809,8 +1809,8 @@ toolbar#nav-bar {
         except AttributeError:
             pass
         try:
-            if options.topsrcdir:
-                sandbox_whitelist_paths.append(options.topsrcdir)
+            if options.objPath:
+                sandbox_whitelist_paths.append(options.objPath)
         except AttributeError:
             pass
         if (platform.system() == "Linux" or