vendor/libc++/libc++-trunk-r300422

6 files changed, 1849 insertions, 0 deletions

diff --git a/utils/libcxx/test/__init__.py b/utils/libcxx/test/__init__.py
new file mode 100644
index 0000000000000..e69de29bb2d1d
--- /dev/null
+++ b/utils/libcxx/test/__init__.py
diff --git a/utils/libcxx/test/config.py b/utils/libcxx/test/config.py
new file mode 100644
index 0000000000000..c941f65b2c572
--- /dev/null
+++ b/utils/libcxx/test/config.py
@@ -0,0 +1,1069 @@
+#===----------------------------------------------------------------------===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===##
+
+import locale
+import os
+import platform
+import pkgutil
+import pipes
+import re
+import shlex
+import shutil
+import sys
+
+from libcxx.compiler import CXXCompiler
+from libcxx.test.target_info import make_target_info
+from libcxx.test.executor import *
+from libcxx.test.tracing import *
+import libcxx.util
+
+def loadSiteConfig(lit_config, config, param_name, env_name):
+    # We haven't loaded the site specific configuration (the user is
+    # probably trying to run on a test file directly, and either the site
+    # configuration hasn't been created by the build system, or we are in an
+    # out-of-tree build situation).
+    site_cfg = lit_config.params.get(param_name,
+                                     os.environ.get(env_name))
+    if not site_cfg:
+        lit_config.warning('No site specific configuration file found!'
+                           ' Running the tests in the default configuration.')
+    elif not os.path.isfile(site_cfg):
+        lit_config.fatal(
+            "Specified site configuration file does not exist: '%s'" %
+            site_cfg)
+    else:
+        lit_config.note('using site specific configuration at %s' % site_cfg)
+        ld_fn = lit_config.load_config
+
+        # Null out the load_config function so that lit.site.cfg doesn't
+        # recursively load a config even if it tries.
+        # TODO: This is one hell of a hack. Fix it.
+        def prevent_reload_fn(*args, **kwargs):
+            pass
+        lit_config.load_config = prevent_reload_fn
+        ld_fn(config, site_cfg)
+        lit_config.load_config = ld_fn
+
+class Configuration(object):
+    # pylint: disable=redefined-outer-name
+    def __init__(self, lit_config, config):
+        self.lit_config = lit_config
+        self.config = config
+        self.is_windows = platform.system() == 'Windows'
+        self.cxx = None
+        self.cxx_is_clang_cl = None
+        self.cxx_stdlib_under_test = None
+        self.project_obj_root = None
+        self.libcxx_src_root = None
+        self.libcxx_obj_root = None
+        self.cxx_library_root = None
+        self.cxx_runtime_root = None
+        self.abi_library_root = None
+        self.link_shared = self.get_lit_bool('enable_shared', default=True)
+        self.debug_build = self.get_lit_bool('debug_build',   default=False)
+        self.exec_env = {}
+        self.use_target = False
+        self.use_system_cxx_lib = False
+        self.use_clang_verify = False
+        self.long_tests = None
+        self.execute_external = False
+
+    def get_lit_conf(self, name, default=None):
+        val = self.lit_config.params.get(name, None)
+        if val is None:
+            val = getattr(self.config, name, None)
+            if val is None:
+                val = default
+        return val
+
+    def get_lit_bool(self, name, default=None, env_var=None):
+        def check_value(value, var_name):
+            if value is None:
+                return default
+            if isinstance(value, bool):
+                return value
+            if not isinstance(value, str):
+                raise TypeError('expected bool or string')
+            if value.lower() in ('1', 'true'):
+                return True
+            if value.lower() in ('', '0', 'false'):
+                return False
+            self.lit_config.fatal(
+                "parameter '{}' should be true or false".format(var_name))
+
+        conf_val = self.get_lit_conf(name)
+        if env_var is not None and env_var in os.environ and \
+                os.environ[env_var] is not None:
+            val = os.environ[env_var]
+            if conf_val is not None:
+                self.lit_config.warning(
+                    'Environment variable %s=%s is overriding explicit '
+                    '--param=%s=%s' % (env_var, val, name, conf_val))
+            return check_value(val, env_var)
+        return check_value(conf_val, name)
+
+    def make_static_lib_name(self, name):
+        """Return the full filename for the specified library name"""
+        if self.is_windows:
+            return name + '.lib'
+        else:
+            return 'lib' + name + '.a'
+
+    def configure(self):
+        self.configure_executor()
+        self.configure_use_system_cxx_lib()
+        self.configure_target_info()
+        self.configure_cxx()
+        self.configure_triple()
+        self.configure_deployment()
+        self.configure_src_root()
+        self.configure_obj_root()
+        self.configure_cxx_stdlib_under_test()
+        self.configure_cxx_library_root()
+        self.configure_use_clang_verify()
+        self.configure_use_thread_safety()
+        self.configure_execute_external()
+        self.configure_ccache()
+        self.configure_compile_flags()
+        self.configure_filesystem_compile_flags()
+        self.configure_link_flags()
+        self.configure_env()
+        self.configure_color_diagnostics()
+        self.configure_debug_mode()
+        self.configure_warnings()
+        self.configure_sanitizer()
+        self.configure_coverage()
+        self.configure_modules()
+        self.configure_substitutions()
+        self.configure_features()
+
+    def print_config_info(self):
+        # Print the final compile and link flags.
+        self.lit_config.note('Using compiler: %s' % self.cxx.path)
+        self.lit_config.note('Using flags: %s' % self.cxx.flags)
+        if self.cxx.use_modules:
+            self.lit_config.note('Using modules flags: %s' %
+                                 self.cxx.modules_flags)
+        self.lit_config.note('Using compile flags: %s'
+                             % self.cxx.compile_flags)
+        if len(self.cxx.warning_flags):
+            self.lit_config.note('Using warnings: %s' % self.cxx.warning_flags)
+        self.lit_config.note('Using link flags: %s' % self.cxx.link_flags)
+        # Print as list to prevent "set([...])" from being printed.
+        self.lit_config.note('Using available_features: %s' %
+                             list(self.config.available_features))
+        self.lit_config.note('Using environment: %r' % self.exec_env)
+        sys.stderr.flush()  # Force flushing to avoid broken output on Windows
+
+    def get_test_format(self):
+        from libcxx.test.format import LibcxxTestFormat
+        return LibcxxTestFormat(
+            self.cxx,
+            self.use_clang_verify,
+            self.execute_external,
+            self.executor,
+            exec_env=self.exec_env)
+
+    def configure_executor(self):
+        exec_str = self.get_lit_conf('executor', "None")
+        te = eval(exec_str)
+        if te:
+            self.lit_config.note("Using executor: %r" % exec_str)
+            if self.lit_config.useValgrind:
+                # We have no way of knowing where in the chain the
+                # ValgrindExecutor is supposed to go. It is likely
+                # that the user wants it at the end, but we have no
+                # way of getting at that easily.
+                selt.lit_config.fatal("Cannot infer how to create a Valgrind "
+                                      " executor.")
+        else:
+            te = LocalExecutor()
+            if self.lit_config.useValgrind:
+                te = ValgrindExecutor(self.lit_config.valgrindArgs, te)
+        self.executor = te
+
+    def configure_target_info(self):
+        self.target_info = make_target_info(self)
+
+    def configure_cxx(self):
+        # Gather various compiler parameters.
+        cxx = self.get_lit_conf('cxx_under_test')
+        self.cxx_is_clang_cl = cxx is not None and \
+                               os.path.basename(cxx) == 'clang-cl.exe'
+        # If no specific cxx_under_test was given, attempt to infer it as
+        # clang++.
+        if cxx is None or self.cxx_is_clang_cl:
+            search_paths = self.config.environment['PATH']
+            if cxx is not None and os.path.isabs(cxx):
+                search_paths = os.path.dirname(cxx)
+            clangxx = libcxx.util.which('clang++', search_paths)
+            if clangxx:
+                cxx = clangxx
+                self.lit_config.note(
+                    "inferred cxx_under_test as: %r" % cxx)
+            elif self.cxx_is_clang_cl:
+                self.lit_config.fatal('Failed to find clang++ substitution for'
+                                      ' clang-cl')
+        if not cxx:
+            self.lit_config.fatal('must specify user parameter cxx_under_test '
+                                  '(e.g., --param=cxx_under_test=clang++)')
+        self.cxx = CXXCompiler(cxx) if not self.cxx_is_clang_cl else \
+                   self._configure_clang_cl(cxx)
+        cxx_type = self.cxx.type
+        if cxx_type is not None:
+            assert self.cxx.version is not None
+            maj_v, min_v, _ = self.cxx.version
+            self.config.available_features.add(cxx_type)
+            self.config.available_features.add('%s-%s' % (cxx_type, maj_v))
+            self.config.available_features.add('%s-%s.%s' % (
+                cxx_type, maj_v, min_v))
+        self.cxx.compile_env = dict(os.environ)
+        # 'CCACHE_CPP2' prevents ccache from stripping comments while
+        # preprocessing. This is required to prevent stripping of '-verify'
+        # comments.
+        self.cxx.compile_env['CCACHE_CPP2'] = '1'
+
+    def _configure_clang_cl(self, clang_path):
+        def _split_env_var(var):
+            return [p.strip() for p in os.environ.get(var, '').split(';') if p.strip()]
+
+        def _prefixed_env_list(var, prefix):
+            from itertools import chain
+            return list(chain.from_iterable((prefix, path) for path in _split_env_var(var)))
+
+        assert self.cxx_is_clang_cl
+        flags = []
+        compile_flags = _prefixed_env_list('INCLUDE', '-isystem')
+        link_flags = _prefixed_env_list('LIB', '-L')
+        for path in _list_env_var('LIB'):
+            self.add_path(self.exec_env, path)
+        return CXXCompiler(clang_path, flags=flags,
+                           compile_flags=compile_flags,
+                           link_flags=link_flags)
+
+
+    def configure_src_root(self):
+        self.libcxx_src_root = self.get_lit_conf(
+            'libcxx_src_root', os.path.dirname(self.config.test_source_root))
+
+    def configure_obj_root(self):
+        self.project_obj_root = self.get_lit_conf('project_obj_root')
+        self.libcxx_obj_root = self.get_lit_conf('libcxx_obj_root')
+        if not self.libcxx_obj_root and self.project_obj_root is not None:
+            possible_root = os.path.join(self.project_obj_root, 'projects', 'libcxx')
+            if os.path.isdir(possible_root):
+                self.libcxx_obj_root = possible_root
+            else:
+                self.libcxx_obj_root = self.project_obj_root
+
+    def configure_cxx_library_root(self):
+        self.cxx_library_root = self.get_lit_conf('cxx_library_root',
+                                                  self.libcxx_obj_root)
+        self.cxx_runtime_root = self.get_lit_conf('cxx_runtime_root',
+                                                   self.cxx_library_root)
+
+    def configure_use_system_cxx_lib(self):
+        # This test suite supports testing against either the system library or
+        # the locally built one; the former mode is useful for testing ABI
+        # compatibility between the current headers and a shipping dynamic
+        # library.
+        # Default to testing against the locally built libc++ library.
+        self.use_system_cxx_lib = self.get_lit_conf('use_system_cxx_lib')
+        if self.use_system_cxx_lib == 'true':
+            self.use_system_cxx_lib = True
+        elif self.use_system_cxx_lib == 'false':
+            self.use_system_cxx_lib = False
+        elif self.use_system_cxx_lib:
+            assert os.path.isdir(self.use_system_cxx_lib)
+        self.lit_config.note(
+            "inferred use_system_cxx_lib as: %r" % self.use_system_cxx_lib)
+
+    def configure_cxx_stdlib_under_test(self):
+        self.cxx_stdlib_under_test = self.get_lit_conf(
+            'cxx_stdlib_under_test', 'libc++')
+        if self.cxx_stdlib_under_test not in \
+                ['libc++', 'libstdc++', 'msvc', 'cxx_default']:
+            self.lit_config.fatal(
+                'unsupported value for "cxx_stdlib_under_test": %s'
+                % self.cxx_stdlib_under_test)
+        self.config.available_features.add(self.cxx_stdlib_under_test)
+        if self.cxx_stdlib_under_test == 'libstdc++':
+            self.config.available_features.add('libstdc++')
+            # Manually enable the experimental and filesystem tests for libstdc++
+            # if the options aren't present.
+            # FIXME this is a hack.
+            if self.get_lit_conf('enable_experimental') is None:
+                self.config.enable_experimental = 'true'
+            if self.get_lit_conf('enable_filesystem') is None:
+                self.config.enable_filesystem = 'true'
+
+    def configure_use_clang_verify(self):
+        '''If set, run clang with -verify on failing tests.'''
+        self.use_clang_verify = self.get_lit_bool('use_clang_verify')
+        if self.use_clang_verify is None:
+            # NOTE: We do not test for the -verify flag directly because
+            #   -verify will always exit with non-zero on an empty file.
+            self.use_clang_verify = self.cxx.isVerifySupported()
+            if self.use_clang_verify:
+                self.config.available_features.add('verify-support')
+            self.lit_config.note(
+                "inferred use_clang_verify as: %r" % self.use_clang_verify)
+
+    def configure_use_thread_safety(self):
+        '''If set, run clang with -verify on failing tests.'''
+        has_thread_safety = self.cxx.hasCompileFlag('-Werror=thread-safety')
+        if has_thread_safety:
+            self.cxx.compile_flags += ['-Werror=thread-safety']
+            self.config.available_features.add('thread-safety')
+            self.lit_config.note("enabling thread-safety annotations")
+
+    def configure_execute_external(self):
+        # Choose between lit's internal shell pipeline runner and a real shell.
+        # If LIT_USE_INTERNAL_SHELL is in the environment, we use that as the
+        # default value. Otherwise we ask the target_info.
+        use_lit_shell_default = os.environ.get('LIT_USE_INTERNAL_SHELL')
+        if use_lit_shell_default is not None:
+            use_lit_shell_default = use_lit_shell_default != '0'
+        else:
+            use_lit_shell_default = self.target_info.use_lit_shell_default()
+        # Check for the command line parameter using the default value if it is
+        # not present.
+        use_lit_shell = self.get_lit_bool('use_lit_shell',
+                                          use_lit_shell_default)
+        self.execute_external = not use_lit_shell
+
+    def configure_ccache(self):
+        use_ccache_default = os.environ.get('LIBCXX_USE_CCACHE') is not None
+        use_ccache = self.get_lit_bool('use_ccache', use_ccache_default)
+        if use_ccache:
+            self.cxx.use_ccache = True
+            self.lit_config.note('enabling ccache')
+
+    def configure_features(self):
+        additional_features = self.get_lit_conf('additional_features')
+        if additional_features:
+            for f in additional_features.split(','):
+                self.config.available_features.add(f.strip())
+        self.target_info.add_locale_features(self.config.available_features)
+
+        target_platform = self.target_info.platform()
+
+        # Write an "available feature" that combines the triple when
+        # use_system_cxx_lib is enabled. This is so that we can easily write
+        # XFAIL markers for tests that are known to fail with versions of
+        # libc++ as were shipped with a particular triple.
+        if self.use_system_cxx_lib:
+            self.config.available_features.add('with_system_cxx_lib')
+            self.config.available_features.add(
+                'with_system_cxx_lib=%s' % self.config.target_triple)
+
+        # Insert the platform name into the available features as a lower case.
+        self.config.available_features.add(target_platform)
+
+        # If we're using deployment, add sub-components of the triple using
+        # "darwin" instead of the platform name.
+        if self.use_deployment:
+            arch, _, _ = self.config.deployment
+            self.config.available_features.add('apple-darwin')
+            self.config.available_features.add(arch + '-apple-darwin')
+
+        # Simulator testing can take a really long time for some of these tests
+        # so add a feature check so we can REQUIRES: long_tests in them
+        self.long_tests = self.get_lit_bool('long_tests')
+        if self.long_tests is None:
+            # Default to running long tests.
+            self.long_tests = True
+            self.lit_config.note(
+                "inferred long_tests as: %r" % self.long_tests)
+
+        if self.long_tests:
+            self.config.available_features.add('long_tests')
+
+        # Run a compile test for the -fsized-deallocation flag. This is needed
+        # in test/std/language.support/support.dynamic/new.delete
+        if self.cxx.hasCompileFlag('-fsized-deallocation'):
+            self.config.available_features.add('fsized-deallocation')
+
+        if self.cxx.hasCompileFlag('-faligned-allocation'):
+            self.config.available_features.add('-faligned-allocation')
+        else:
+            # FIXME remove this once more than just clang-4.0 support
+            # C++17 aligned allocation.
+            self.config.available_features.add('no-aligned-allocation')
+
+        if self.get_lit_bool('has_libatomic', False):
+            self.config.available_features.add('libatomic')
+
+        macros = self.cxx.dumpMacros()
+        if '__cpp_if_constexpr' not in macros:
+            self.config.available_features.add('libcpp-no-if-constexpr')
+
+        if '__cpp_structured_bindings' not in macros:
+            self.config.available_features.add('libcpp-no-structured-bindings')
+
+        if '__cpp_deduction_guides' not in macros:
+            self.config.available_features.add('libcpp-no-deduction-guides')
+
+        if self.is_windows:
+            self.config.available_features.add('windows')
+
+        # Attempt to detect the glibc version by querying for __GLIBC__
+        # in 'features.h'.
+        macros = self.cxx.dumpMacros(flags=['-include', 'features.h'])
+        if macros is not None and '__GLIBC__' in macros:
+            maj_v, min_v = (macros['__GLIBC__'], macros['__GLIBC_MINOR__'])
+            self.config.available_features.add('glibc')
+            self.config.available_features.add('glibc-%s' % maj_v)
+            self.config.available_features.add('glibc-%s.%s' % (maj_v, min_v))
+
+    def configure_compile_flags(self):
+        no_default_flags = self.get_lit_bool('no_default_flags', False)
+        if not no_default_flags:
+            self.configure_default_compile_flags()
+        # This include is always needed so add so add it regardless of
+        # 'no_default_flags'.
+        support_path = os.path.join(self.libcxx_src_root, 'test/support')
+        self.cxx.compile_flags += ['-I' + support_path]
+        # Configure extra flags
+        compile_flags_str = self.get_lit_conf('compile_flags', '')
+        self.cxx.compile_flags += shlex.split(compile_flags_str)
+        # FIXME: Can we remove this?
+        if self.is_windows:
+            self.cxx.compile_flags += ['-D_CRT_SECURE_NO_WARNINGS']
+
+    def configure_default_compile_flags(self):
+        # Try and get the std version from the command line. Fall back to
+        # default given in lit.site.cfg is not present. If default is not
+        # present then force c++11.
+        std = self.get_lit_conf('std')
+        if not std:
+            # Choose the newest possible language dialect if none is given.
+            possible_stds = ['c++1z', 'c++14', 'c++11', 'c++03']
+            if self.cxx.type == 'gcc':
+                maj_v, _, _ = self.cxx.version
+                maj_v = int(maj_v)
+                if maj_v < 7:
+                    possible_stds.remove('c++1z')
+                # FIXME: How many C++14 tests actually fail under GCC 5 and 6?
+                # Should we XFAIL them individually instead?
+                if maj_v <= 6:
+                    possible_stds.remove('c++14')
+            for s in possible_stds:
+                if self.cxx.hasCompileFlag('-std=%s' % s):
+                    std = s
+                    self.lit_config.note(
+                        'inferred language dialect as: %s' % std)
+                    break
+            if not std:
+                self.lit_config.fatal(
+                    'Failed to infer a supported language dialect from one of %r'
+                    % possible_stds)
+        self.cxx.compile_flags += ['-std={0}'.format(std)]
+        self.config.available_features.add(std.replace('gnu++', 'c++'))
+        # Configure include paths
+        self.configure_compile_flags_header_includes()
+        self.target_info.add_cxx_compile_flags(self.cxx.compile_flags)
+        # Configure feature flags.
+        self.configure_compile_flags_exceptions()
+        self.configure_compile_flags_rtti()
+        self.configure_compile_flags_abi_version()
+        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')
+        if sysroot:
+            self.cxx.flags += ['--sysroot', sysroot]
+        gcc_toolchain = self.get_lit_conf('gcc_toolchain')
+        if gcc_toolchain:
+            self.cxx.flags += ['-gcc-toolchain', gcc_toolchain]
+        # NOTE: the _DEBUG definition must preceed the triple check because for
+        # the Windows build of libc++, the forced inclusion of a header requires
+        # that _DEBUG is defined.  Incorrect ordering will result in -target
+        # being elided.
+        if self.is_windows and self.debug_build:
+            self.cxx.compile_flags += ['-D_DEBUG']
+        if self.use_target:
+            if not self.cxx.addFlagIfSupported(
+                    ['-target', self.config.target_triple]):
+                self.lit_config.warning('use_target is true but -target is '\
+                        'not supported by the compiler')
+        if self.use_deployment:
+            arch, name, version = self.config.deployment
+            self.cxx.flags += ['-arch', arch]
+            self.cxx.flags += ['-m' + name + '-version-min=' + version]
+
+    def configure_compile_flags_header_includes(self):
+        support_path = os.path.join(self.libcxx_src_root, 'test', 'support')
+        if self.cxx_stdlib_under_test != 'libstdc++' and \
+           not self.is_windows:
+            self.cxx.compile_flags += [
+                '-include', os.path.join(support_path, 'nasty_macros.hpp')]
+        if self.cxx_stdlib_under_test == 'msvc':
+            self.cxx.compile_flags += [
+                '-include', os.path.join(support_path,
+                                         'msvc_stdlib_force_include.hpp')]
+            pass
+        if self.is_windows and self.debug_build and \
+                self.cxx_stdlib_under_test != 'msvc':
+            self.cxx.compile_flags += [
+                '-include', os.path.join(support_path,
+                                         'set_windows_crt_report_mode.h')
+            ]
+        self.configure_config_site_header()
+        cxx_headers = self.get_lit_conf('cxx_headers')
+        if cxx_headers == '' or (cxx_headers is None
+                                 and self.cxx_stdlib_under_test != 'libc++'):
+            self.lit_config.note('using the system cxx headers')
+            return
+        self.cxx.compile_flags += ['-nostdinc++']
+        if cxx_headers is None:
+            cxx_headers = os.path.join(self.libcxx_src_root, 'include')
+        if not os.path.isdir(cxx_headers):
+            self.lit_config.fatal("cxx_headers='%s' is not a directory."
+                                  % cxx_headers)
+        self.cxx.compile_flags += ['-I' + cxx_headers]
+        if self.libcxx_obj_root is not None:
+            cxxabi_headers = os.path.join(self.libcxx_obj_root, 'include',
+                                          'c++build')
+            if os.path.isdir(cxxabi_headers):
+                self.cxx.compile_flags += ['-I' + cxxabi_headers]
+
+    def configure_config_site_header(self):
+        # Check for a possible __config_site in the build directory. We
+        # use this if it exists.
+        if self.libcxx_obj_root is None:
+            return
+        config_site_header = os.path.join(self.libcxx_obj_root, '__config_site')
+        if not os.path.isfile(config_site_header):
+            return
+        contained_macros = self.parse_config_site_and_add_features(
+            config_site_header)
+        self.lit_config.note('Using __config_site header %s with macros: %r'
+            % (config_site_header, contained_macros))
+        # FIXME: This must come after the call to
+        # 'parse_config_site_and_add_features(...)' in order for it to work.
+        self.cxx.compile_flags += ['-include', config_site_header]
+
+    def parse_config_site_and_add_features(self, header):
+        """ parse_config_site_and_add_features - Deduce and add the test
+            features that that are implied by the #define's in the __config_site
+            header. Return a dictionary containing the macros found in the
+            '__config_site' header.
+        """
+        # Parse the macro contents of __config_site by dumping the macros
+        # using 'c++ -dM -E' and filtering the predefines.
+        predefines = self.cxx.dumpMacros()
+        macros = self.cxx.dumpMacros(header)
+        feature_macros_keys = set(macros.keys()) - set(predefines.keys())
+        feature_macros = {}
+        for k in feature_macros_keys:
+            feature_macros[k] = macros[k]
+        # We expect the header guard to be one of the definitions
+        assert '_LIBCPP_CONFIG_SITE' in feature_macros
+        del feature_macros['_LIBCPP_CONFIG_SITE']
+        # The __config_site header should be non-empty. Otherwise it should
+        # have never been emitted by CMake.
+        assert len(feature_macros) > 0
+        # Transform each macro name into the feature name used in the tests.
+        # Ex. _LIBCPP_HAS_NO_THREADS -> libcpp-has-no-threads
+        for m in feature_macros:
+            if m == '_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS':
+                continue
+            if m == '_LIBCPP_ABI_VERSION':
+                self.config.available_features.add('libcpp-abi-version-v%s'
+                    % feature_macros[m])
+                continue
+            assert m.startswith('_LIBCPP_HAS_') or m == '_LIBCPP_ABI_UNSTABLE'
+            m = m.lower()[1:].replace('_', '-')
+            self.config.available_features.add(m)
+        return feature_macros
+
+
+
+    def configure_compile_flags_exceptions(self):
+        enable_exceptions = self.get_lit_bool('enable_exceptions', True)
+        if not enable_exceptions:
+            self.config.available_features.add('libcpp-no-exceptions')
+            self.cxx.compile_flags += ['-fno-exceptions']
+
+    def configure_compile_flags_rtti(self):
+        enable_rtti = self.get_lit_bool('enable_rtti', True)
+        if not enable_rtti:
+            self.config.available_features.add('libcpp-no-rtti')
+            self.cxx.compile_flags += ['-fno-rtti', '-D_LIBCPP_NO_RTTI']
+
+    def configure_compile_flags_abi_version(self):
+        abi_version = self.get_lit_conf('abi_version', '').strip()
+        abi_unstable = self.get_lit_bool('abi_unstable')
+        # Only add the ABI version when it is non-default.
+        # FIXME(EricWF): Get the ABI version from the "__config_site".
+        if abi_version and abi_version != '1':
+          self.cxx.compile_flags += ['-D_LIBCPP_ABI_VERSION=' + abi_version]
+        if abi_unstable:
+          self.config.available_features.add('libcpp-abi-unstable')
+          self.cxx.compile_flags += ['-D_LIBCPP_ABI_UNSTABLE']
+
+    def configure_filesystem_compile_flags(self):
+        enable_fs = self.get_lit_bool('enable_filesystem', default=False)
+        if not enable_fs:
+            return
+        enable_experimental = self.get_lit_bool('enable_experimental', default=False)
+        if not enable_experimental:
+            self.lit_config.fatal(
+                'filesystem is enabled but libc++experimental.a is not.')
+        self.config.available_features.add('c++filesystem')
+        static_env = os.path.join(self.libcxx_src_root, 'test', 'std',
+                                  'experimental', 'filesystem', 'Inputs', 'static_test_env')
+        static_env = os.path.realpath(static_env)
+        assert os.path.isdir(static_env)
+        self.cxx.compile_flags += ['-DLIBCXX_FILESYSTEM_STATIC_TEST_ROOT="%s"' % static_env]
+
+        dynamic_env = os.path.join(self.config.test_exec_root,
+                                   'filesystem', 'Output', 'dynamic_env')
+        dynamic_env = os.path.realpath(dynamic_env)
+        if not os.path.isdir(dynamic_env):
+            os.makedirs(dynamic_env)
+        self.cxx.compile_flags += ['-DLIBCXX_FILESYSTEM_DYNAMIC_TEST_ROOT="%s"' % dynamic_env]
+        self.exec_env['LIBCXX_FILESYSTEM_DYNAMIC_TEST_ROOT'] = ("%s" % dynamic_env)
+
+        dynamic_helper = os.path.join(self.libcxx_src_root, 'test', 'support',
+                                      'filesystem_dynamic_test_helper.py')
+        assert os.path.isfile(dynamic_helper)
+
+        self.cxx.compile_flags += ['-DLIBCXX_FILESYSTEM_DYNAMIC_TEST_HELPER="%s %s"'
+                                   % (sys.executable, dynamic_helper)]
+
+
+    def configure_link_flags(self):
+        no_default_flags = self.get_lit_bool('no_default_flags', False)
+        if not no_default_flags:
+            # Configure library path
+            self.configure_link_flags_cxx_library_path()
+            self.configure_link_flags_abi_library_path()
+
+            # Configure libraries
+            if self.cxx_stdlib_under_test == 'libc++':
+                self.cxx.link_flags += ['-nodefaultlibs']
+                # FIXME: Handle MSVCRT as part of the ABI library handling.
+                if self.is_windows:
+                    self.cxx.link_flags += ['-nostdlib']
+                self.configure_link_flags_cxx_library()
+                self.configure_link_flags_abi_library()
+                self.configure_extra_library_flags()
+            elif self.cxx_stdlib_under_test == 'libstdc++':
+                enable_fs = self.get_lit_bool('enable_filesystem',
+                                              default=False)
+                if enable_fs:
+                    self.config.available_features.add('c++experimental')
+                    self.cxx.link_flags += ['-lstdc++fs']
+                self.cxx.link_flags += ['-lm', '-pthread']
+            elif self.cxx_stdlib_under_test == 'msvc':
+                # FIXME: Correctly setup debug/release flags here.
+                pass
+            elif self.cxx_stdlib_under_test == 'cxx_default':
+                self.cxx.link_flags += ['-pthread']
+            else:
+                self.lit_config.fatal(
+                    'unsupported value for "use_stdlib_type": %s'
+                    %  use_stdlib_type)
+
+        link_flags_str = self.get_lit_conf('link_flags', '')
+        self.cxx.link_flags += shlex.split(link_flags_str)
+
+    def configure_link_flags_cxx_library_path(self):
+        if not self.use_system_cxx_lib:
+            if self.cxx_library_root:
+                self.cxx.link_flags += ['-L' + self.cxx_library_root]
+                if self.is_windows and self.link_shared:
+                    self.add_path(self.cxx.compile_env, self.cxx_library_root)
+            if self.cxx_runtime_root:
+                if not self.is_windows:
+                    self.cxx.link_flags += ['-Wl,-rpath,' +
+                                            self.cxx_runtime_root]
+                elif self.is_windows and self.link_shared:
+                    self.add_path(self.exec_env, self.cxx_runtime_root)
+        elif os.path.isdir(str(self.use_system_cxx_lib)):
+            self.cxx.link_flags += ['-L' + self.use_system_cxx_lib]
+            if not self.is_windows:
+                self.cxx.link_flags += ['-Wl,-rpath,' +
+                                        self.use_system_cxx_lib]
+            if self.is_windows and self.link_shared:
+                self.add_path(self.cxx.compile_env, self.use_system_cxx_lib)
+
+    def configure_link_flags_abi_library_path(self):
+        # Configure ABI library paths.
+        self.abi_library_root = self.get_lit_conf('abi_library_path')
+        if self.abi_library_root:
+            self.cxx.link_flags += ['-L' + self.abi_library_root]
+            if not self.is_windows:
+                self.cxx.link_flags += ['-Wl,-rpath,' + self.abi_library_root]
+            else:
+                self.add_path(self.exec_env, self.abi_library_root)
+
+    def configure_link_flags_cxx_library(self):
+        libcxx_experimental = self.get_lit_bool('enable_experimental', default=False)
+        if libcxx_experimental:
+            self.config.available_features.add('c++experimental')
+            self.cxx.link_flags += ['-lc++experimental']
+        if self.link_shared:
+            self.cxx.link_flags += ['-lc++']
+        else:
+            cxx_library_root = self.get_lit_conf('cxx_library_root')
+            if cxx_library_root:
+                libname = self.make_static_lib_name('c++')
+                abs_path = os.path.join(cxx_library_root, libname)
+                assert os.path.exists(abs_path) and \
+                       "static libc++ library does not exist"
+                self.cxx.link_flags += [abs_path]
+            else:
+                self.cxx.link_flags += ['-lc++']
+
+    def configure_link_flags_abi_library(self):
+        cxx_abi = self.get_lit_conf('cxx_abi', 'libcxxabi')
+        if cxx_abi == 'libstdc++':
+            self.cxx.link_flags += ['-lstdc++']
+        elif cxx_abi == 'libsupc++':
+            self.cxx.link_flags += ['-lsupc++']
+        elif cxx_abi == 'libcxxabi':
+            if self.target_info.allow_cxxabi_link():
+                libcxxabi_shared = self.get_lit_bool('libcxxabi_shared', default=True)
+                if libcxxabi_shared:
+                    self.cxx.link_flags += ['-lc++abi']
+                else:
+                    cxxabi_library_root = self.get_lit_conf('abi_library_path')
+                    if cxxabi_library_root:
+                        libname = self.make_static_lib_name('c++abi')
+                        abs_path = os.path.join(cxxabi_library_root, libname)
+                        self.cxx.link_flags += [abs_path]
+                    else:
+                        self.cxx.link_flags += ['-lc++abi']
+        elif cxx_abi == 'libcxxrt':
+            self.cxx.link_flags += ['-lcxxrt']
+        elif cxx_abi == 'vcruntime':
+            debug_suffix = 'd' if self.debug_build else ''
+            self.cxx.link_flags += ['-l%s%s' % (lib, debug_suffix) for lib in
+                                    ['vcruntime', 'ucrt', 'msvcrt']]
+        elif cxx_abi == 'none' or cxx_abi == 'default':
+            if self.is_windows:
+                debug_suffix = 'd' if self.debug_build else ''
+                self.cxx.link_flags += ['-lmsvcrt%s' % debug_suffix]
+        else:
+            self.lit_config.fatal(
+                'C++ ABI setting %s unsupported for tests' % cxx_abi)
+
+    def configure_extra_library_flags(self):
+        if self.get_lit_bool('cxx_ext_threads', default=False):
+            self.cxx.link_flags += ['-lc++external_threads']
+        self.target_info.add_cxx_link_flags(self.cxx.link_flags)
+
+    def configure_color_diagnostics(self):
+        use_color = self.get_lit_conf('color_diagnostics')
+        if use_color is None:
+            use_color = os.environ.get('LIBCXX_COLOR_DIAGNOSTICS')
+        if use_color is None:
+            return
+        if use_color != '':
+            self.lit_config.fatal('Invalid value for color_diagnostics "%s".'
+                                  % use_color)
+        color_flag = '-fdiagnostics-color=always'
+        # Check if the compiler supports the color diagnostics flag. Issue a
+        # warning if it does not since color diagnostics have been requested.
+        if not self.cxx.hasCompileFlag(color_flag):
+            self.lit_config.warning(
+                'color diagnostics have been requested but are not supported '
+                'by the compiler')
+        else:
+            self.cxx.flags += [color_flag]
+
+    def configure_debug_mode(self):
+        debug_level = self.get_lit_conf('debug_level', None)
+        if not debug_level:
+            return
+        if debug_level not in ['0', '1']:
+            self.lit_config.fatal('Invalid value for debug_level "%s".'
+                                  % debug_level)
+        self.cxx.compile_flags += ['-D_LIBCPP_DEBUG=%s' % debug_level]
+
+    def configure_warnings(self):
+        # Turn on warnings by default for Clang based compilers when C++ >= 11
+        default_enable_warnings = self.cxx.type in ['clang', 'apple-clang'] \
+            and len(self.config.available_features.intersection(
+                ['c++11', 'c++14', 'c++1z'])) != 0
+        enable_warnings = self.get_lit_bool('enable_warnings',
+                                            default_enable_warnings)
+        self.cxx.useWarnings(enable_warnings)
+        self.cxx.warning_flags += [
+            '-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER',
+            '-Wall', '-Wextra', '-Werror'
+        ]
+        if self.cxx.hasWarningFlag('-Wuser-defined-warnings'):
+            self.cxx.warning_flags += ['-Wuser-defined-warnings']
+            self.config.available_features.add('diagnose-if-support')
+        self.cxx.addWarningFlagIfSupported('-Wshadow')
+        self.cxx.addWarningFlagIfSupported('-Wno-unused-command-line-argument')
+        self.cxx.addWarningFlagIfSupported('-Wno-attributes')
+        self.cxx.addWarningFlagIfSupported('-Wno-pessimizing-move')
+        self.cxx.addWarningFlagIfSupported('-Wno-c++11-extensions')
+        self.cxx.addWarningFlagIfSupported('-Wno-user-defined-literals')
+        self.cxx.addWarningFlagIfSupported('-Wno-noexcept-type')
+        # These warnings should be enabled in order to support the MSVC
+        # team using the test suite; They enable the warnings below and
+        # expect the test suite to be clean.
+        self.cxx.addWarningFlagIfSupported('-Wsign-compare')
+        self.cxx.addWarningFlagIfSupported('-Wunused-variable')
+        self.cxx.addWarningFlagIfSupported('-Wunused-parameter')
+        self.cxx.addWarningFlagIfSupported('-Wunreachable-code')
+        # FIXME: Enable the two warnings below.
+        self.cxx.addWarningFlagIfSupported('-Wno-conversion')
+        self.cxx.addWarningFlagIfSupported('-Wno-unused-local-typedef')
+        std = self.get_lit_conf('std', None)
+        if std in ['c++98', 'c++03']:
+            # The '#define static_assert' provided by libc++ in C++03 mode
+            # causes an unused local typedef whenever it is used.
+            self.cxx.addWarningFlagIfSupported('-Wno-unused-local-typedef')
+
+    def configure_sanitizer(self):
+        san = self.get_lit_conf('use_sanitizer', '').strip()
+        if san:
+            self.target_info.add_sanitizer_features(san, self.config.available_features)
+            # Search for llvm-symbolizer along the compiler path first
+            # and then along the PATH env variable.
+            symbolizer_search_paths = os.environ.get('PATH', '')
+            cxx_path = libcxx.util.which(self.cxx.path)
+            if cxx_path is not None:
+                symbolizer_search_paths = (
+                    os.path.dirname(cxx_path) +
+                    os.pathsep + symbolizer_search_paths)
+            llvm_symbolizer = libcxx.util.which('llvm-symbolizer',
+                                                symbolizer_search_paths)
+
+            def add_ubsan():
+                self.cxx.flags += ['-fsanitize=undefined',
+                                   '-fno-sanitize=vptr,function,float-divide-by-zero',
+                                   '-fno-sanitize-recover=all']
+                self.exec_env['UBSAN_OPTIONS'] = 'print_stacktrace=1'
+                self.config.available_features.add('ubsan')
+
+            # Setup the sanitizer compile flags
+            self.cxx.flags += ['-g', '-fno-omit-frame-pointer']
+            if san == 'Address' or san == 'Address;Undefined' or san == 'Undefined;Address':
+                self.cxx.flags += ['-fsanitize=address']
+                if llvm_symbolizer is not None:
+                    self.exec_env['ASAN_SYMBOLIZER_PATH'] = llvm_symbolizer
+                # FIXME: Turn ODR violation back on after PR28391 is resolved
+                # https://bugs.llvm.org/show_bug.cgi?id=28391
+                self.exec_env['ASAN_OPTIONS'] = 'detect_odr_violation=0'
+                self.config.available_features.add('asan')
+                self.config.available_features.add('sanitizer-new-delete')
+                self.cxx.compile_flags += ['-O1']
+                if san == 'Address;Undefined' or san == 'Undefined;Address':
+                    add_ubsan()
+            elif san == 'Memory' or san == 'MemoryWithOrigins':
+                self.cxx.flags += ['-fsanitize=memory']
+                if san == 'MemoryWithOrigins':
+                    self.cxx.compile_flags += [
+                        '-fsanitize-memory-track-origins']
+                if llvm_symbolizer is not None:
+                    self.exec_env['MSAN_SYMBOLIZER_PATH'] = llvm_symbolizer
+                self.config.available_features.add('msan')
+                self.config.available_features.add('sanitizer-new-delete')
+                self.cxx.compile_flags += ['-O1']
+            elif san == 'Undefined':
+                add_ubsan()
+                self.cxx.compile_flags += ['-O2']
+            elif san == 'Thread':
+                self.cxx.flags += ['-fsanitize=thread']
+                self.config.available_features.add('tsan')
+                self.config.available_features.add('sanitizer-new-delete')
+            else:
+                self.lit_config.fatal('unsupported value for '
+                                      'use_sanitizer: {0}'.format(san))
+            san_lib = self.get_lit_conf('sanitizer_library')
+            if san_lib:
+                self.cxx.link_flags += [
+                    san_lib, '-Wl,-rpath,%s' % os.path.dirname(san_lib)]
+
+    def configure_coverage(self):
+        self.generate_coverage = self.get_lit_bool('generate_coverage', False)
+        if self.generate_coverage:
+            self.cxx.flags += ['-g', '--coverage']
+            self.cxx.compile_flags += ['-O0']
+
+    def configure_modules(self):
+        modules_flags = ['-fmodules']
+        if platform.system() != 'Darwin':
+            modules_flags += ['-Xclang', '-fmodules-local-submodule-visibility']
+        supports_modules = self.cxx.hasCompileFlag(modules_flags)
+        enable_modules = self.get_lit_bool('enable_modules',
+                                           default=False,
+                                           env_var='LIBCXX_ENABLE_MODULES')
+        if enable_modules and not supports_modules:
+            self.lit_config.fatal(
+                '-fmodules is enabled but not supported by the compiler')
+        if not supports_modules:
+            return
+        self.config.available_features.add('modules-support')
+        module_cache = os.path.join(self.config.test_exec_root,
+                                   'modules.cache')
+        module_cache = os.path.realpath(module_cache)
+        if os.path.isdir(module_cache):
+            shutil.rmtree(module_cache)
+        os.makedirs(module_cache)
+        self.cxx.modules_flags = modules_flags + \
+            ['-fmodules-cache-path=' + module_cache]
+        if enable_modules:
+            self.config.available_features.add('-fmodules')
+            self.cxx.useModules()
+
+    def configure_substitutions(self):
+        sub = self.config.substitutions
+        cxx_path = pipes.quote(self.cxx.path)
+        # Configure compiler substitutions
+        sub.append(('%cxx', cxx_path))
+        # Configure flags substitutions
+        flags_str = ' '.join([pipes.quote(f) for f in self.cxx.flags])
+        compile_flags_str = ' '.join([pipes.quote(f) for f in self.cxx.compile_flags])
+        link_flags_str = ' '.join([pipes.quote(f) for f in self.cxx.link_flags])
+        all_flags = '%s %s %s' % (flags_str, compile_flags_str, link_flags_str)
+        sub.append(('%flags', flags_str))
+        sub.append(('%compile_flags', compile_flags_str))
+        sub.append(('%link_flags', link_flags_str))
+        sub.append(('%all_flags', all_flags))
+        if self.cxx.isVerifySupported():
+            verify_str = ' ' + ' '.join(self.cxx.verify_flags) + ' '
+            sub.append(('%verify', verify_str))
+        # Add compile and link shortcuts
+        compile_str = (cxx_path + ' -o %t.o %s -c ' + flags_str
+                       + ' ' + compile_flags_str)
+        link_str = (cxx_path + ' -o %t.exe %t.o ' + flags_str + ' '
+                    + link_flags_str)
+        assert type(link_str) is str
+        build_str = cxx_path + ' -o %t.exe %s ' + all_flags
+        if self.cxx.use_modules:
+            sub.append(('%compile_module', compile_str))
+            sub.append(('%build_module', build_str))
+        elif self.cxx.modules_flags is not None:
+            modules_str = ' '.join(self.cxx.modules_flags) + ' '
+            sub.append(('%compile_module', compile_str + ' ' + modules_str))
+            sub.append(('%build_module', build_str + ' ' + modules_str))
+        sub.append(('%compile', compile_str))
+        sub.append(('%link', link_str))
+        sub.append(('%build', build_str))
+        # Configure exec prefix substitutions.
+        exec_env_str = ''
+        if not self.is_windows and len(self.exec_env) != 0:
+            exec_env_str = 'env '
+            for k, v in self.exec_env.items():
+                exec_env_str += ' %s=%s' % (k, v)
+        # Configure run env substitution.
+        exec_str = exec_env_str
+        if self.lit_config.useValgrind:
+            exec_str = ' '.join(self.lit_config.valgrindArgs) + exec_env_str
+        sub.append(('%exec', exec_str))
+        # Configure run shortcut
+        sub.append(('%run', exec_str + ' %t.exe'))
+        # Configure not program substitutions
+        not_py = os.path.join(self.libcxx_src_root, 'utils', 'not.py')
+        not_str = '%s %s ' % (pipes.quote(sys.executable), pipes.quote(not_py))
+        sub.append(('not ', not_str))
+
+    def can_use_deployment(self):
+        # Check if the host is on an Apple platform using clang.
+        if not self.target_info.platform() == "darwin":
+            return False
+        if not self.target_info.is_host_macosx():
+            return False
+        if not self.cxx.type.endswith('clang'):
+            return False
+        return True
+
+    def configure_triple(self):
+        # Get or infer the target triple.
+        target_triple = self.get_lit_conf('target_triple')
+        self.use_target = self.get_lit_bool('use_target', False)
+        if self.use_target and target_triple:
+            self.lit_config.warning('use_target is true but no triple is specified')
+
+        # Use deployment if possible.
+        self.use_deployment = not self.use_target and self.can_use_deployment()
+        if self.use_deployment:
+            return
+
+        # Save the triple (and warn on Apple platforms).
+        self.config.target_triple = target_triple
+        if self.use_target and 'apple' in target_triple:
+            self.lit_config.warning('consider using arch and platform instead'
+                                    ' of target_triple on Apple platforms')
+
+        # If no target triple was given, try to infer it from the compiler
+        # under test.
+        if not self.config.target_triple:
+            target_triple = self.cxx.getTriple()
+            # Drop sub-major version components from the triple, because the
+            # current XFAIL handling expects exact matches for feature checks.
+            # Example: x86_64-apple-darwin14.0.0 -> x86_64-apple-darwin14
+            # The 5th group handles triples greater than 3 parts
+            # (ex x86_64-pc-linux-gnu).
+            target_triple = re.sub(r'([^-]+)-([^-]+)-([^.]+)([^-]*)(.*)',
+                                   r'\1-\2-\3\5', target_triple)
+            # linux-gnu is needed in the triple to properly identify linuxes
+            # that use GLIBC. Handle redhat and opensuse triples as special
+            # cases and append the missing `-gnu` portion.
+            if (target_triple.endswith('redhat-linux') or
+                target_triple.endswith('suse-linux')):
+                target_triple += '-gnu'
+            self.config.target_triple = target_triple
+            self.lit_config.note(
+                "inferred target_triple as: %r" % self.config.target_triple)
+
+    def configure_deployment(self):
+        assert not self.use_deployment is None
+        assert not self.use_target is None
+        if not self.use_deployment:
+            # Warn about ignored parameters.
+            if self.get_lit_conf('arch'):
+                self.lit_config.warning('ignoring arch, using target_triple')
+            if self.get_lit_conf('platform'):
+                self.lit_config.warning('ignoring platform, using target_triple')
+            return
+
+        assert not self.use_target
+        assert self.target_info.is_host_macosx()
+
+        # Always specify deployment explicitly on Apple platforms, since
+        # otherwise a platform is picked up from the SDK.  If the SDK version
+        # doesn't match the system version, tests that use the system library
+        # may fail spuriously.
+        arch = self.get_lit_conf('arch')
+        if not arch:
+            arch = self.cxx.getTriple().split('-', 1)[0]
+            self.lit_config.note("inferred arch as: %r" % arch)
+
+        inferred_platform, name, version = self.target_info.get_platform()
+        if inferred_platform:
+            self.lit_config.note("inferred platform as: %r" % (name + version))
+        self.config.deployment = (arch, name, version)
+
+        # Set the target triple for use by lit.
+        self.config.target_triple = arch + '-apple-' + name + version
+        self.lit_config.note(
+            "computed target_triple as: %r" % self.config.target_triple)
+
+    def configure_env(self):
+        self.target_info.configure_env(self.exec_env)
+
+    def add_path(self, dest_env, new_path):
+        if 'PATH' not in dest_env:
+            dest_env['PATH'] = new_path
+        else:
+            split_char = ';' if self.is_windows else ':'
+            dest_env['PATH'] = '%s%s%s' % (new_path, split_char,
+                                           dest_env['PATH'])
diff --git a/utils/libcxx/test/executor.py b/utils/libcxx/test/executor.py
new file mode 100644
index 0000000000000..4a189174d915c
--- /dev/null
+++ b/utils/libcxx/test/executor.py
@@ -0,0 +1,223 @@
+#===----------------------------------------------------------------------===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===##
+
+import platform
+import os
+
+from libcxx.test import tracing
+from libcxx.util import executeCommand
+
+
+class Executor(object):
+    def run(self, exe_path, cmd, local_cwd, file_deps=None, env=None):
+        """Execute a command.
+            Be very careful not to change shared state in this function.
+            Executor objects are shared between python processes in `lit -jN`.
+        Args:
+            exe_path: str:    Local path to the executable to be run
+            cmd: [str]:       subprocess.call style command
+            local_cwd: str:   Local path to the working directory
+            file_deps: [str]: Files required by the test
+            env: {str: str}:  Environment variables to execute under
+        Returns:
+            cmd, out, err, exitCode
+        """
+        raise NotImplementedError
+
+
+class LocalExecutor(Executor):
+    def __init__(self):
+        super(LocalExecutor, self).__init__()
+        self.is_windows = platform.system() == 'Windows'
+
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
+        cmd = cmd or [exe_path]
+        env_cmd = []
+        if env:
+            env_cmd += ['env']
+            env_cmd += ['%s=%s' % (k, v) for k, v in env.items()]
+        if work_dir == '.':
+            work_dir = os.getcwd()
+        if not self.is_windows:
+            out, err, rc = executeCommand(env_cmd + cmd, cwd=work_dir)
+        else:
+            out, err, rc = executeCommand(cmd, cwd=work_dir,
+                                          env=self._build_windows_env(env))
+        return (env_cmd + cmd, out, err, rc)
+
+    def _build_windows_env(self, exec_env):
+        # FIXME: Finding Windows DLL's at runtime requires modifying the
+        #   PATH environment variables. However we don't want to print out
+        #   the entire PATH as part of the diagnostic for every failing test.
+        #   Therefore this hack builds a new executable environment that
+        #   merges the current environment and the supplied environment while
+        #   still only printing the supplied environment in diagnostics.
+        if not self.is_windows or exec_env is None:
+            return None
+        new_env = dict(os.environ)
+        for key, value in exec_env.items():
+            if key == 'PATH':
+                assert value.strip() != '' and "expected non-empty path"
+                new_env['PATH'] = "%s;%s" % (value, os.environ['PATH'])
+            else:
+                new_env[key] = value
+        return new_env
+
+class PrefixExecutor(Executor):
+    """Prefix an executor with some other command wrapper.
+
+    Most useful for setting ulimits on commands, or running an emulator like
+    qemu and valgrind.
+    """
+    def __init__(self, commandPrefix, chain):
+        super(PrefixExecutor, self).__init__()
+
+        self.commandPrefix = commandPrefix
+        self.chain = chain
+
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
+        cmd = cmd or [exe_path]
+        return self.chain.run(exe_path, self.commandPrefix + cmd, work_dir,
+                              file_deps, env=env)
+
+
+class PostfixExecutor(Executor):
+    """Postfix an executor with some args."""
+    def __init__(self, commandPostfix, chain):
+        super(PostfixExecutor, self).__init__()
+
+        self.commandPostfix = commandPostfix
+        self.chain = chain
+
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
+        cmd = cmd or [exe_path]
+        return self.chain.run(cmd + self.commandPostfix, work_dir, file_deps,
+                              env=env)
+
+
+
+class TimeoutExecutor(PrefixExecutor):
+    """Execute another action under a timeout.
+
+    Deprecated. http://reviews.llvm.org/D6584 adds timeouts to LIT.
+    """
+    def __init__(self, duration, chain):
+        super(TimeoutExecutor, self).__init__(
+            ['timeout', duration], chain)
+
+
+class RemoteExecutor(Executor):
+    def __init__(self):
+        self.local_run = executeCommand
+
+    def remote_temp_dir(self):
+        return self._remote_temp(True)
+
+    def remote_temp_file(self):
+        return self._remote_temp(False)
+
+    def _remote_temp(self, is_dir):
+        raise NotImplementedError()
+
+    def copy_in(self, local_srcs, remote_dsts):
+        # This could be wrapped up in a tar->scp->untar for performance
+        # if there are lots of files to be copied/moved
+        for src, dst in zip(local_srcs, remote_dsts):
+            self._copy_in_file(src, dst)
+
+    def _copy_in_file(self, src, dst):
+        raise NotImplementedError()
+
+    def delete_remote(self, remote):
+        try:
+            self._execute_command_remote(['rm', '-rf', remote])
+        except OSError:
+            # TODO: Log failure to delete?
+            pass
+
+    def run(self, exe_path, cmd=None, work_dir='.', file_deps=None, env=None):
+        target_exe_path = None
+        target_cwd = None
+        try:
+            target_cwd = self.remote_temp_dir()
+            target_exe_path = os.path.join(target_cwd, 'libcxx_test.exe')
+            if cmd:
+                # Replace exe_path with target_exe_path.
+                cmd = [c if c != exe_path else target_exe_path for c in cmd]
+            else:
+                cmd = [target_exe_path]
+
+            srcs = [exe_path]
+            dsts = [target_exe_path]
+            if file_deps is not None:
+                dev_paths = [os.path.join(target_cwd, os.path.basename(f))
+                             for f in file_deps]
+                srcs.extend(file_deps)
+                dsts.extend(dev_paths)
+            self.copy_in(srcs, dsts)
+            # TODO(jroelofs): capture the copy_in and delete_remote commands,
+            # and conjugate them with '&&'s around the first tuple element
+            # returned here:
+            return self._execute_command_remote(cmd, target_cwd, env)
+        finally:
+            if target_cwd:
+                self.delete_remote(target_cwd)
+
+    def _execute_command_remote(self, cmd, remote_work_dir='.', env=None):
+        raise NotImplementedError()
+
+
+class SSHExecutor(RemoteExecutor):
+    def __init__(self, host, username=None):
+        super(SSHExecutor, self).__init__()
+
+        self.user_prefix = username + '@' if username else ''
+        self.host = host
+        self.scp_command = 'scp'
+        self.ssh_command = 'ssh'
+
+        # TODO(jroelofs): switch this on some -super-verbose-debug config flag
+        if False:
+            self.local_run = tracing.trace_function(
+                self.local_run, log_calls=True, log_results=True,
+                label='ssh_local')
+
+    def _remote_temp(self, is_dir):
+        # TODO: detect what the target system is, and use the correct
+        # mktemp command for it. (linux and darwin differ here, and I'm
+        # sure windows has another way to do it)
+
+        # Not sure how to do suffix on osx yet
+        dir_arg = '-d' if is_dir else ''
+        cmd = 'mktemp -q {} /tmp/libcxx.XXXXXXXXXX'.format(dir_arg)
+        _, temp_path, err, exitCode = self._execute_command_remote([cmd])
+        temp_path = temp_path.strip()
+        if exitCode != 0:
+            raise RuntimeError(err)
+        return temp_path
+
+    def _copy_in_file(self, src, dst):
+        scp = self.scp_command
+        remote = self.host
+        remote = self.user_prefix + remote
+        cmd = [scp, '-p', src, remote + ':' + dst]
+        self.local_run(cmd)
+
+    def _execute_command_remote(self, cmd, remote_work_dir='.', env=None):
+        remote = self.user_prefix + self.host
+        ssh_cmd = [self.ssh_command, '-oBatchMode=yes', remote]
+        if env:
+            env_cmd = ['env'] + ['%s=%s' % (k, v) for k, v in env.items()]
+        else:
+            env_cmd = []
+        remote_cmd = ' '.join(env_cmd + cmd)
+        if remote_work_dir != '.':
+            remote_cmd = 'cd ' + remote_work_dir + ' && ' + remote_cmd
+        out, err, rc = self.local_run(ssh_cmd + [remote_cmd])
+        return (remote_cmd, out, err, rc)
diff --git a/utils/libcxx/test/format.py b/utils/libcxx/test/format.py
new file mode 100644
index 0000000000000..c3bc97187ad45
--- /dev/null
+++ b/utils/libcxx/test/format.py
@@ -0,0 +1,238 @@
+#===----------------------------------------------------------------------===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===##
+
+import copy
+import errno
+import os
+import time
+import random
+
+import lit.Test        # pylint: disable=import-error
+import lit.TestRunner  # pylint: disable=import-error
+from lit.TestRunner import ParserKind, IntegratedTestKeywordParser  \
+    # pylint: disable=import-error
+
+from libcxx.test.executor import LocalExecutor as LocalExecutor
+import libcxx.util
+
+
+class LibcxxTestFormat(object):
+    """
+    Custom test format handler for use with the test format use by libc++.
+
+    Tests fall into two categories:
+      FOO.pass.cpp - Executable test which should compile, run, and exit with
+                     code 0.
+      FOO.fail.cpp - Negative test case which is expected to fail compilation.
+      FOO.sh.cpp   - A test that uses LIT's ShTest format.
+    """
+
+    def __init__(self, cxx, use_verify_for_fail, execute_external,
+                 executor, exec_env):
+        self.cxx = copy.deepcopy(cxx)
+        self.use_verify_for_fail = use_verify_for_fail
+        self.execute_external = execute_external
+        self.executor = executor
+        self.exec_env = dict(exec_env)
+
+    @staticmethod
+    def _make_custom_parsers():
+        return [
+            IntegratedTestKeywordParser('FLAKY_TEST.', ParserKind.TAG,
+                                        initial_value=False),
+            IntegratedTestKeywordParser('MODULES_DEFINES:', ParserKind.LIST,
+                                        initial_value=[])
+        ]
+
+    @staticmethod
+    def _get_parser(key, parsers):
+        for p in parsers:
+            if p.keyword == key:
+                return p
+        assert False and "parser not found"
+
+    # TODO: Move this into lit's FileBasedTest
+    def getTestsInDirectory(self, testSuite, path_in_suite,
+                            litConfig, localConfig):
+        source_path = testSuite.getSourcePath(path_in_suite)
+        for filename in os.listdir(source_path):
+            # Ignore dot files and excluded tests.
+            if filename.startswith('.') or filename in localConfig.excludes:
+                continue
+
+            filepath = os.path.join(source_path, filename)
+            if not os.path.isdir(filepath):
+                if any([filename.endswith(ext)
+                        for ext in localConfig.suffixes]):
+                    yield lit.Test.Test(testSuite, path_in_suite + (filename,),
+                                        localConfig)
+
+    def execute(self, test, lit_config):
+        while True:
+            try:
+                return self._execute(test, lit_config)
+            except OSError as oe:
+                if oe.errno != errno.ETXTBSY:
+                    raise
+                time.sleep(0.1)
+
+    def _execute(self, test, lit_config):
+        name = test.path_in_suite[-1]
+        name_root, name_ext = os.path.splitext(name)
+        is_libcxx_test = test.path_in_suite[0] == 'libcxx'
+        is_sh_test = name_root.endswith('.sh')
+        is_pass_test = name.endswith('.pass.cpp')
+        is_fail_test = name.endswith('.fail.cpp')
+        assert is_sh_test or name_ext == '.cpp', 'non-cpp file must be sh test'
+
+        if test.config.unsupported:
+            return (lit.Test.UNSUPPORTED,
+                    "A lit.local.cfg marked this unsupported")
+
+        parsers = self._make_custom_parsers()
+        script = lit.TestRunner.parseIntegratedTestScript(
+            test, additional_parsers=parsers, require_script=is_sh_test)
+        # Check if a result for the test was returned. If so return that
+        # result.
+        if isinstance(script, lit.Test.Result):
+            return script
+        if lit_config.noExecute:
+            return lit.Test.Result(lit.Test.PASS)
+
+        # Check that we don't have run lines on tests that don't support them.
+        if not is_sh_test and len(script) != 0:
+            lit_config.fatal('Unsupported RUN line found in test %s' % name)
+
+        tmpDir, tmpBase = lit.TestRunner.getTempPaths(test)
+        substitutions = lit.TestRunner.getDefaultSubstitutions(test, tmpDir,
+                                                               tmpBase)
+        script = lit.TestRunner.applySubstitutions(script, substitutions)
+
+        test_cxx = copy.deepcopy(self.cxx)
+        if is_fail_test:
+            test_cxx.useCCache(False)
+            test_cxx.useWarnings(False)
+        extra_modules_defines = self._get_parser('MODULES_DEFINES:',
+                                                 parsers).getValue()
+        if '-fmodules' in test.config.available_features:
+            test_cxx.compile_flags += [('-D%s' % mdef.strip()) for
+                                       mdef in extra_modules_defines]
+            test_cxx.addWarningFlagIfSupported('-Wno-macro-redefined')
+            # FIXME: libc++ debug tests #define _LIBCPP_ASSERT to override it
+            # If we see this we need to build the test against uniquely built
+            # modules.
+            if is_libcxx_test:
+                with open(test.getSourcePath(), 'r') as f:
+                    contents = f.read()
+                if '#define _LIBCPP_ASSERT' in contents:
+                    test_cxx.useModules(False)
+
+        # Dispatch the test based on its suffix.
+        if is_sh_test:
+            if not isinstance(self.executor, LocalExecutor):
+                # We can't run ShTest tests with a executor yet.
+                # For now, bail on trying to run them
+                return lit.Test.UNSUPPORTED, 'ShTest format not yet supported'
+            test.config.enviroment = dict(self.exec_env)
+            return lit.TestRunner._runShTest(test, lit_config,
+                                             self.execute_external, script,
+                                             tmpBase)
+        elif is_fail_test:
+            return self._evaluate_fail_test(test, test_cxx, parsers)
+        elif is_pass_test:
+            return self._evaluate_pass_test(test, tmpBase, lit_config,
+                                            test_cxx, parsers)
+        else:
+            # No other test type is supported
+            assert False
+
+    def _clean(self, exec_path):  # pylint: disable=no-self-use
+        libcxx.util.cleanFile(exec_path)
+
+    def _evaluate_pass_test(self, test, tmpBase, lit_config,
+                            test_cxx, parsers):
+        execDir = os.path.dirname(test.getExecPath())
+        source_path = test.getSourcePath()
+        exec_path = tmpBase + '.exe'
+        object_path = tmpBase + '.o'
+        # Create the output directory if it does not already exist.
+        libcxx.util.mkdir_p(os.path.dirname(tmpBase))
+        try:
+            # Compile the test
+            cmd, out, err, rc = test_cxx.compileLinkTwoSteps(
+                source_path, out=exec_path, object_file=object_path,
+                cwd=execDir)
+            compile_cmd = cmd
+            if rc != 0:
+                report = libcxx.util.makeReport(cmd, out, err, rc)
+                report += "Compilation failed unexpectedly!"
+                return lit.Test.FAIL, report
+            # Run the test
+            local_cwd = os.path.dirname(source_path)
+            env = None
+            if self.exec_env:
+                env = self.exec_env
+            # TODO: Only list actually needed files in file_deps.
+            # Right now we just mark all of the .dat files in the same
+            # directory as dependencies, but it's likely less than that. We
+            # should add a `// FILE-DEP: foo.dat` to each test to track this.
+            data_files = [os.path.join(local_cwd, f)
+                          for f in os.listdir(local_cwd) if f.endswith('.dat')]
+            is_flaky = self._get_parser('FLAKY_TEST.', parsers).getValue()
+            max_retry = 3 if is_flaky else 1
+            for retry_count in range(max_retry):
+                cmd, out, err, rc = self.executor.run(exec_path, [exec_path],
+                                                      local_cwd, data_files,
+                                                      env)
+                if rc == 0:
+                    res = lit.Test.PASS if retry_count == 0 else lit.Test.FLAKYPASS
+                    return res, ''
+                elif rc != 0 and retry_count + 1 == max_retry:
+                    report = libcxx.util.makeReport(cmd, out, err, rc)
+                    report = "Compiled With: %s\n%s" % (compile_cmd, report)
+                    report += "Compiled test failed unexpectedly!"
+                    return lit.Test.FAIL, report
+
+            assert False # Unreachable
+        finally:
+            # Note that cleanup of exec_file happens in `_clean()`. If you
+            # override this, cleanup is your reponsibility.
+            libcxx.util.cleanFile(object_path)
+            self._clean(exec_path)
+
+    def _evaluate_fail_test(self, test, test_cxx, parsers):
+        source_path = test.getSourcePath()
+        # FIXME: lift this detection into LLVM/LIT.
+        with open(source_path, 'r') as f:
+            contents = f.read()
+        verify_tags = ['expected-note', 'expected-remark', 'expected-warning',
+                       'expected-error', 'expected-no-diagnostics']
+        use_verify = self.use_verify_for_fail and \
+                     any([tag in contents for tag in verify_tags])
+        # FIXME(EricWF): GCC 5 does not evaluate static assertions that
+        # are dependant on a template parameter when '-fsyntax-only' is passed.
+        # This is fixed in GCC 6. However for now we only pass "-fsyntax-only"
+        # when using Clang.
+        if test_cxx.type != 'gcc':
+            test_cxx.flags += ['-fsyntax-only']
+        if use_verify:
+            test_cxx.useVerify()
+            test_cxx.useWarnings()
+            if '-Wuser-defined-warnings' in test_cxx.warning_flags:
+                test_cxx.warning_flags += ['-Wno-error=user-defined-warnings']
+
+        cmd, out, err, rc = test_cxx.compile(source_path, out=os.devnull)
+        expected_rc = 0 if use_verify else 1
+        if rc == expected_rc:
+            return lit.Test.PASS, ''
+        else:
+            report = libcxx.util.makeReport(cmd, out, err, rc)
+            report_msg = ('Expected compilation to fail!' if not use_verify else
+                          'Expected compilation using verify to pass!')
+            return lit.Test.FAIL, report + report_msg + '\n'
diff --git a/utils/libcxx/test/target_info.py b/utils/libcxx/test/target_info.py
new file mode 100644
index 0000000000000..9a7ae05a0285c
--- /dev/null
+++ b/utils/libcxx/test/target_info.py
@@ -0,0 +1,276 @@
+#===----------------------------------------------------------------------===//
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===//
+
+import importlib
+import lit.util  # pylint: disable=import-error,no-name-in-module
+import locale
+import os
+import platform
+import re
+import sys
+
+class DefaultTargetInfo(object):
+    def __init__(self, full_config):
+        self.full_config = full_config
+
+    def platform(self):
+        return sys.platform.lower().strip()
+
+    def add_locale_features(self, features):
+        self.full_config.lit_config.warning(
+            "No locales entry for target_system: %s" % self.platform())
+
+    def add_cxx_compile_flags(self, flags): pass
+    def add_cxx_link_flags(self, flags): pass
+    def configure_env(self, env): pass
+    def allow_cxxabi_link(self): return True
+    def add_sanitizer_features(self, sanitizer_type, features): pass
+    def use_lit_shell_default(self): return False
+
+
+def test_locale(loc):
+    assert loc is not None
+    default_locale = locale.setlocale(locale.LC_ALL)
+    try:
+        locale.setlocale(locale.LC_ALL, loc)
+        return True
+    except locale.Error:
+        return False
+    finally:
+        locale.setlocale(locale.LC_ALL, default_locale)
+
+
+def add_common_locales(features, lit_config):
+    # A list of locales needed by the test-suite.
+    # The list uses the canonical name for the locale used in the test-suite
+    # TODO: On Linux ISO8859 *may* needs to hyphenated.
+    locales = [
+        'en_US.UTF-8',
+        'fr_FR.UTF-8',
+        'ru_RU.UTF-8',
+        'zh_CN.UTF-8',
+        'fr_CA.ISO8859-1',
+        'cs_CZ.ISO8859-2'
+    ]
+    for loc in locales:
+        if test_locale(loc):
+            features.add('locale.{0}'.format(loc))
+        else:
+            lit_config.warning('The locale {0} is not supported by '
+                               'your platform. Some tests will be '
+                               'unsupported.'.format(loc))
+
+
+class DarwinLocalTI(DefaultTargetInfo):
+    def __init__(self, full_config):
+        super(DarwinLocalTI, self).__init__(full_config)
+
+    def is_host_macosx(self):
+        name = lit.util.capture(['sw_vers', '-productName']).strip()
+        return name == "Mac OS X"
+
+    def get_macosx_version(self):
+        assert self.is_host_macosx()
+        version = lit.util.capture(['sw_vers', '-productVersion']).strip()
+        version = re.sub(r'([0-9]+\.[0-9]+)(\..*)?', r'\1', version)
+        return version
+
+    def get_sdk_version(self, name):
+        assert self.is_host_macosx()
+        cmd = ['xcrun', '--sdk', name, '--show-sdk-path']
+        try:
+            out = lit.util.capture(cmd).strip()
+        except OSError:
+            pass
+
+        if not out:
+            self.full_config.lit_config.fatal(
+                    "cannot infer sdk version with: %r" % cmd)
+
+        return re.sub(r'.*/[^0-9]+([0-9.]+)\.sdk', r'\1', out)
+
+    def get_platform(self):
+        platform = self.full_config.get_lit_conf('platform')
+        if platform:
+            platform = re.sub(r'([^0-9]+)([0-9\.]*)', r'\1-\2', platform)
+            name, version = tuple(platform.split('-', 1))
+        else:
+            name = 'macosx'
+            version = None
+
+        if version:
+            return (False, name, version)
+
+        # Infer the version, either from the SDK or the system itself.  For
+        # macosx, ignore the SDK version; what matters is what's at
+        # /usr/lib/libc++.dylib.
+        if name == 'macosx':
+            version = self.get_macosx_version()
+        else:
+            version = self.get_sdk_version(name)
+        return (True, name, version)
+
+    def add_locale_features(self, features):
+        add_common_locales(features, self.full_config.lit_config)
+
+    def add_cxx_compile_flags(self, flags):
+        if self.full_config.use_deployment:
+            _, name, _ = self.full_config.config.deployment
+            cmd = ['xcrun', '--sdk', name, '--show-sdk-path']
+        else:
+            cmd = ['xcrun', '--show-sdk-path']
+        try:
+            out = lit.util.capture(cmd).strip()
+            res = 0
+        except OSError:
+            res = -1
+        if res == 0 and out:
+            sdk_path = out
+            self.full_config.lit_config.note('using SDKROOT: %r' % sdk_path)
+            flags += ["-isysroot", sdk_path]
+
+    def add_cxx_link_flags(self, flags):
+        flags += ['-lSystem']
+
+    def configure_env(self, env):
+        library_paths = []
+        # Configure the library path for libc++
+        if self.full_config.use_system_cxx_lib:
+            if (os.path.isdir(str(self.full_config.use_system_cxx_lib))):
+                library_paths += [self.full_config.use_system_cxx_lib]
+            pass
+        elif self.full_config.cxx_runtime_root:
+            library_paths += [self.full_config.cxx_runtime_root]
+        # Configure the abi library path
+        if self.full_config.abi_library_root:
+            library_paths += [self.full_config.abi_library_root]
+        if library_paths:
+            env['DYLD_LIBRARY_PATH'] = ':'.join(library_paths)
+
+    def allow_cxxabi_link(self):
+        # FIXME: PR27405
+        # libc++ *should* export all of the symbols found in libc++abi on OS X.
+        # For this reason LibcxxConfiguration will not link libc++abi in OS X.
+        # However __cxa_throw_bad_new_array_length doesn't get exported into
+        # libc++ yet so we still need to explicitly link libc++abi when testing
+        # libc++abi
+        # See PR22654.
+        if(self.full_config.get_lit_conf('name', '') == 'libc++abi'):
+            return True
+        # Don't link libc++abi explicitly on OS X because the symbols
+        # should be available in libc++ directly.
+        return False
+
+    def add_sanitizer_features(self, sanitizer_type, features):
+        if sanitizer_type == 'Undefined':
+            features.add('sanitizer-new-delete')
+
+
+class FreeBSDLocalTI(DefaultTargetInfo):
+    def __init__(self, full_config):
+        super(FreeBSDLocalTI, self).__init__(full_config)
+
+    def add_locale_features(self, features):
+        add_common_locales(features, self.full_config.lit_config)
+
+    def add_cxx_link_flags(self, flags):
+        flags += ['-lc', '-lm', '-lpthread', '-lgcc_s', '-lcxxrt']
+
+
+class LinuxLocalTI(DefaultTargetInfo):
+    def __init__(self, full_config):
+        super(LinuxLocalTI, self).__init__(full_config)
+
+    def platform(self):
+        return 'linux'
+
+    def platform_name(self):
+        name, _, _ = platform.linux_distribution()
+        name = name.lower().strip()
+        return name # Permitted to be None
+
+    def platform_ver(self):
+        _, ver, _ = platform.linux_distribution()
+        ver = ver.lower().strip()
+        return ver # Permitted to be None.
+
+    def add_locale_features(self, features):
+        add_common_locales(features, self.full_config.lit_config)
+        # Some linux distributions have different locale data than others.
+        # Insert the distributions name and name-version into the available
+        # features to allow tests to XFAIL on them.
+        name = self.platform_name()
+        ver = self.platform_ver()
+        if name:
+            features.add(name)
+        if name and ver:
+            features.add('%s-%s' % (name, ver))
+
+    def add_cxx_compile_flags(self, flags):
+        flags += ['-D__STDC_FORMAT_MACROS',
+                  '-D__STDC_LIMIT_MACROS',
+                  '-D__STDC_CONSTANT_MACROS']
+
+    def add_cxx_link_flags(self, flags):
+        enable_threads = ('libcpp-has-no-threads' not in
+                          self.full_config.config.available_features)
+        llvm_unwinder = self.full_config.get_lit_bool('llvm_unwinder', False)
+        shared_libcxx = self.full_config.get_lit_bool('enable_shared', True)
+        flags += ['-lm']
+        if not llvm_unwinder:
+            flags += ['-lgcc_s', '-lgcc']
+        if enable_threads:
+            flags += ['-lpthread']
+            if not shared_libcxx:
+              flags += ['-lrt']
+        flags += ['-lc']
+        if llvm_unwinder:
+            flags += ['-lunwind', '-ldl']
+        else:
+            flags += ['-lgcc_s']
+        flags += ['-lgcc']
+        use_libatomic = self.full_config.get_lit_bool('use_libatomic', False)
+        if use_libatomic:
+            flags += ['-latomic']
+        san = self.full_config.get_lit_conf('use_sanitizer', '').strip()
+        if san:
+            # The libraries and their order are taken from the
+            # linkSanitizerRuntimeDeps function in
+            # clang/lib/Driver/Tools.cpp
+            flags += ['-lpthread', '-lrt', '-lm', '-ldl']
+
+
+class WindowsLocalTI(DefaultTargetInfo):
+    def __init__(self, full_config):
+        super(WindowsLocalTI, self).__init__(full_config)
+
+    def add_locale_features(self, features):
+        add_common_locales(features, self.full_config.lit_config)
+
+    def use_lit_shell_default(self):
+        # Default to the internal shell on Windows, as bash on Windows is
+        # usually very slow.
+        return True
+
+
+def make_target_info(full_config):
+    default = "libcxx.test.target_info.LocalTI"
+    info_str = full_config.get_lit_conf('target_info', default)
+    if info_str != default:
+        mod_path, _, info = info_str.rpartition('.')
+        mod = importlib.import_module(mod_path)
+        target_info = getattr(mod, info)(full_config)
+        full_config.lit_config.note("inferred target_info as: %r" % info_str)
+        return target_info
+    target_system = platform.system()
+    if target_system == 'Darwin':  return DarwinLocalTI(full_config)
+    if target_system == 'FreeBSD': return FreeBSDLocalTI(full_config)
+    if target_system == 'Linux':   return LinuxLocalTI(full_config)
+    if target_system == 'Windows': return WindowsLocalTI(full_config)
+    return DefaultTargetInfo(full_config)
diff --git a/utils/libcxx/test/tracing.py b/utils/libcxx/test/tracing.py
new file mode 100644
index 0000000000000..c590ba3efd014
--- /dev/null
+++ b/utils/libcxx/test/tracing.py
@@ -0,0 +1,43 @@
+#===----------------------------------------------------------------------===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===##
+
+import os
+import inspect
+
+
+def trace_function(function, log_calls, log_results, label=''):
+    def wrapper(*args, **kwargs):
+        kwarg_strs = ['{}={}'.format(k, v) for (k, v) in kwargs]
+        arg_str = ', '.join([str(a) for a in args] + kwarg_strs)
+        call_str = '{}({})'.format(function.func_name, arg_str)
+
+        # Perform the call itself, logging before, after, and anything thrown.
+        try:
+            if log_calls:
+                print('{}: Calling {}'.format(label, call_str))
+            res = function(*args, **kwargs)
+            if log_results:
+                print('{}: {} -> {}'.format(label, call_str, res))
+            return res
+        except Exception as ex:
+            if log_results:
+                print('{}: {} raised {}'.format(label, call_str, type(ex)))
+            raise ex
+
+    return wrapper
+
+
+def trace_object(obj, log_calls, log_results, label=''):
+    for name, member in inspect.getmembers(obj):
+        if inspect.ismethod(member):
+            # Skip meta-functions, decorate everything else
+            if not member.func_name.startswith('__'):
+                setattr(obj, name, trace_function(member, log_calls,
+                                                  log_results, label))
+    return obj