diff --git a/libcxx/test/CMakeLists.txt b/libcxx/test/CMakeLists.txt
--- a/libcxx/test/CMakeLists.txt
+++ b/libcxx/test/CMakeLists.txt
@@ -113,6 +113,10 @@
   serialize_lit_param(use_sanitizer "\"${LLVM_USE_SANITIZER}\"")
 endif()
 
+if (LIBCXX_BUILD_32_BITS)
+  serialize_lit_param(enable_32bit True)
+endif()
+
 if (NOT DEFINED LIBCXX_TEST_DEPS)
   message(FATAL_ERROR "Expected LIBCXX_TEST_DEPS to be defined")
 endif()
diff --git a/libcxx/test/configs/legacy.cfg.in b/libcxx/test/configs/legacy.cfg.in
--- a/libcxx/test/configs/legacy.cfg.in
+++ b/libcxx/test/configs/legacy.cfg.in
@@ -13,7 +13,6 @@
 config.cxx_library_root         = "@LIBCXX_LIBRARY_DIR@"
 config.abi_library_root         = "@LIBCXX_CXX_ABI_LIBRARY_PATH@"
 config.enable_shared            = @LIBCXX_LINK_TESTS_WITH_SHARED_LIBCXX@
-config.enable_32bit             = @LIBCXX_BUILD_32_BITS@
 config.cxx_abi                  = "@LIBCXX_CXX_ABI_LIBNAME@"
 config.configuration_variant    = "@LIBCXX_LIT_VARIANT@"
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
diff --git a/libcxx/utils/libcxx/test/config.py b/libcxx/utils/libcxx/test/config.py
--- a/libcxx/utils/libcxx/test/config.py
+++ b/libcxx/utils/libcxx/test/config.py
@@ -267,10 +267,6 @@
         self.configure_compile_flags_header_includes()
         self.target_info.add_cxx_compile_flags(self.cxx.compile_flags)
         self.target_info.add_cxx_flags(self.cxx.flags)
-        # Configure feature flags.
-        enable_32bit = self.get_lit_bool('enable_32bit', False)
-        if enable_32bit:
-            self.cxx.flags += ['-m32']
         # Use verbose output for better errors
         self.cxx.flags += ['-v']
         sysroot = self.get_lit_conf('sysroot')
diff --git a/libcxx/utils/libcxx/test/params.py b/libcxx/utils/libcxx/test/params.py
--- a/libcxx/utils/libcxx/test/params.py
+++ b/libcxx/utils/libcxx/test/params.py
@@ -158,6 +158,13 @@
               AddFeature('libcxx-no-debug-mode')
             ]),
 
+  Parameter(name='enable_32bit', choices=[True, False], type=bool, default=False,
+            help="Whether to build the test suite in 32 bit mode even on a 64 bit target. This basically controls "
+                 "whether -m32 is used when building the test suite.",
+            actions=lambda enabled: [] if not enabled else [
+              AddFlag('-m32')
+            ]),
+
   Parameter(name='additional_features', type=list, default=[],
             help="A comma-delimited list of additional features that will be enabled when running the tests. "
                  "This should be used sparingly since specifying ad-hoc features manually is error-prone and "
diff --git a/libcxxabi/test/CMakeLists.txt b/libcxxabi/test/CMakeLists.txt
--- a/libcxxabi/test/CMakeLists.txt
+++ b/libcxxabi/test/CMakeLists.txt
@@ -90,6 +90,10 @@
   serialize_lit_param(target_triple "\"${TARGET_TRIPLE}\"")
 endif()
 
+if (LIBCXXABI_BUILD_32_BITS)
+  serialize_lit_param(enable_32bit True)
+endif()
+
 configure_lit_site_cfg(
   "${LIBCXXABI_TEST_CONFIG}"
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
diff --git a/libcxxabi/test/lit.site.cfg.in b/libcxxabi/test/lit.site.cfg.in
--- a/libcxxabi/test/lit.site.cfg.in
+++ b/libcxxabi/test/lit.site.cfg.in
@@ -18,7 +18,6 @@
 config.llvm_unwinder            = @LIBCXXABI_USE_LLVM_UNWINDER@
 config.builtins_library         = "@LIBCXXABI_BUILTINS_LIBRARY@"
 config.enable_threads           = @LIBCXXABI_ENABLE_THREADS@
-config.enable_32bit             = @LIBCXXABI_BUILD_32_BITS@
 config.target_info              = "@LIBCXXABI_TARGET_INFO@"
 config.executor                 = "@LIBCXXABI_EXECUTOR@"
 config.libcxxabi_shared         = @LIBCXXABI_LINK_TESTS_WITH_SHARED_LIBCXXABI@
diff --git a/libunwind/test/CMakeLists.txt b/libunwind/test/CMakeLists.txt
--- a/libunwind/test/CMakeLists.txt
+++ b/libunwind/test/CMakeLists.txt
@@ -40,6 +40,10 @@
   serialize_lit_param(target_triple "\"${TARGET_TRIPLE}\"")
 endif()
 
+if (LIBUNWIND_BUILD_32_BITS)
+  serialize_lit_param(enable_32bit True)
+endif()
+
 configure_lit_site_cfg(
   "${LIBUNWIND_TEST_CONFIG}"
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
diff --git a/libunwind/test/lit.site.cfg.in b/libunwind/test/lit.site.cfg.in
--- a/libunwind/test/lit.site.cfg.in
+++ b/libunwind/test/lit.site.cfg.in
@@ -16,7 +16,6 @@
 config.llvm_unwinder            = True
 config.builtins_library         = "@LIBUNWIND_BUILTINS_LIBRARY@"
 config.enable_threads           = @LIBUNWIND_ENABLE_THREADS@
-config.enable_32bit             = @LIBUNWIND_BUILD_32_BITS@
 config.target_info              = "@LIBUNWIND_TARGET_INFO@"
 config.test_linker_flags        = "@LIBUNWIND_TEST_LINKER_FLAGS@"
 config.test_compiler_flags      = "@LIBUNWIND_TEST_COMPILER_FLAGS@"