diff --git a/lldb/packages/Python/lldbsuite/test/dotest.py b/lldb/packages/Python/lldbsuite/test/dotest.py
--- a/lldb/packages/Python/lldbsuite/test/dotest.py
+++ b/lldb/packages/Python/lldbsuite/test/dotest.py
@@ -335,6 +335,9 @@
         # that explicitly require no debug info.
         os.environ['CFLAGS'] = '-gdwarf-{}'.format(configuration.dwarf_version)
 
+    if args.custom_libcpp:
+        os.environ['CUSTOM_LIBCPP'] = args.custom_libcpp
+
     if args.settings:
         for setting in args.settings:
             if not len(setting) == 1 or not setting[0].count('='):
diff --git a/lldb/packages/Python/lldbsuite/test/dotest_args.py b/lldb/packages/Python/lldbsuite/test/dotest_args.py
--- a/lldb/packages/Python/lldbsuite/test/dotest_args.py
+++ b/lldb/packages/Python/lldbsuite/test/dotest_args.py
@@ -172,6 +172,11 @@
         type=str,
         metavar='A plugin whose tests will be enabled',
         help='A plugin whose tests will be enabled. The only currently supported plugin is intel-pt.')
+    group.add_argument(
+        '--custom-libcpp',
+        metavar='custom-libcpp',
+        dest='custom_libcpp',
+        help='(Clang only) Specify path to a custom standard library to use. Disables search for other standard C++ libraries.')
 
     # Configuration options
     group = parser.add_argument_group('Remote platform options')
diff --git a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
--- a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
+++ b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
@@ -402,6 +402,14 @@
 	endif
 endif
 
+ifdef CUSTOM_LIBCPP
+        ifeq (,$(findstring clang,$(CC)))
+                $(error "CUSTOM_LIBCPP only supported for Clang compilers")
+        endif
+
+        CXXFLAGS += -nostdinc++ -cxx-isystem $(CUSTOM_LIBCPP)
+endif
+
 #----------------------------------------------------------------------
 # Additional system libraries
 #----------------------------------------------------------------------