diff --git a/libcxx/test/libcxx/selftest/newformat/additional_compile_flags/substitutes-in-compile-flags.sh.cpp b/libcxx/test/libcxx/selftest/newformat/additional_compile_flags/substitutes-in-compile-flags.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/additional_compile_flags/substitutes-in-compile-flags.sh.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure that substitutions are performed inside additional compiler flags.
+
+// ADDITIONAL_COMPILE_FLAGS: -I %t.1
+// ADDITIONAL_COMPILE_FLAGS: -isystem %t.2 , -isysroot %t.3
+// RUN: echo "%{compile_flags}" | grep -e '-I %t.1 -isystem %t.2 -isysroot %t.3'
diff --git a/libcxx/test/libcxx/selftest/newformat/additional_compile_flags/substitutes-in-run.sh.cpp b/libcxx/test/libcxx/selftest/newformat/additional_compile_flags/substitutes-in-run.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/additional_compile_flags/substitutes-in-run.sh.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure that additional compiler flags are added to the %{compile_flags}
+// substitution.
+
+// ADDITIONAL_COMPILE_FLAGS: -foo
+// ADDITIONAL_COMPILE_FLAGS: -bar
+// ADDITIONAL_COMPILE_FLAGS: -baz, -foom
+// RUN: echo "%{compile_flags}" | grep -e '-foo -bar -baz -foom'
diff --git a/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/compile-error.compile.fail.cpp b/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/compile-error.compile.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/compile-error.compile.fail.cpp
@@ -0,0 +1,14 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it fails at compile-time
+
+struct Foo { };
+typedef Foo::x x; // expected-error{{no type named 'x' in 'Foo'}}
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/compile-success.compile.fail.cpp b/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/compile-success.compile.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/compile-success.compile.fail.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it succeeds at compile-time
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/wrong-expected.compile.fail.cpp b/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/wrong-expected.compile.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/compile.fail.cpp/wrong-expected.compile.fail.cpp
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time, but the
+// expected-error is wrong.
+
+struct Foo { };
+typedef Foo::x x; // expected-error{{this is not found in the errors}}
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/compile-error.compile.pass.cpp b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/compile-error.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/compile-error.compile.pass.cpp
@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time
+
+struct Foo { };
+typedef Foo::x x;
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/compile-success.compile.pass.cpp b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/compile-success.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/compile-success.compile.pass.cpp
@@ -0,0 +1,11 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it succeeds to compile
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/link-error.compile.pass.cpp b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/link-error.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/link-error.compile.pass.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes even if there's a link error, i.e. it isn't linked.
+
+extern void this_is_an_undefined_symbol();
+
+int main() {
+    this_is_an_undefined_symbol();
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/run-error.compile.pass.cpp b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/run-error.compile.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/compile.pass.cpp/run-error.compile.pass.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes even if there's a runtime error, i.e. it isn't run.
+
+int main() {
+    return 1;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-error-with-verify.fail.cpp b/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-error-with-verify.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-error-with-verify.fail.cpp
@@ -0,0 +1,14 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it fails at compile-time, with verify
+
+struct Foo { };
+typedef Foo::x x; // expected-error{{no type named 'x' in 'Foo'}}
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-error-without-verify.fail.cpp b/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-error-without-verify.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-error-without-verify.fail.cpp
@@ -0,0 +1,14 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it fails at compile-time, without verify
+
+struct Foo { };
+typedef Foo::x x;
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-success.fail.cpp b/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-success.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/fail.cpp/compile-success.fail.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it succeeds at compile-time
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/fail.cpp/wrong-expected.fail.cpp b/libcxx/test/libcxx/selftest/newformat/fail.cpp/wrong-expected.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/fail.cpp/wrong-expected.fail.cpp
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time, but the
+// expected-error is wrong.
+
+struct Foo { };
+typedef Foo::x x; // expected-error{{this is not found in the errors}}
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/file_dependencies/no-dependencies.sh.cpp b/libcxx/test/libcxx/selftest/newformat/file_dependencies/no-dependencies.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/file_dependencies/no-dependencies.sh.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure that %{file_dependencies} is empty when no FILE_DEPENDENCIES
+// line appears. Amongst other things, this makes sure that we don't share
+// file dependencies across unrelated Lit tests.
+
+// RUN: test -z "%{file_dependencies}"
diff --git a/libcxx/test/libcxx/selftest/newformat/file_dependencies/substitute-in-dependencies.sh.cpp b/libcxx/test/libcxx/selftest/newformat/file_dependencies/substitute-in-dependencies.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/file_dependencies/substitute-in-dependencies.sh.cpp
@@ -0,0 +1,12 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure that lit substitutions are expanded inside FILE_DEPENDENCIES lines.
+
+// FILE_DEPENDENCIES: %s
+// RUN: echo %{file_dependencies} | grep 'substitute-in-dependencies.sh.cpp'
diff --git a/libcxx/test/libcxx/selftest/newformat/file_dependencies/substitute-in-run.sh.cpp b/libcxx/test/libcxx/selftest/newformat/file_dependencies/substitute-in-run.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/file_dependencies/substitute-in-run.sh.cpp
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure %{file_dependencies} are substituted properly into RUN commands.
+
+// FILE_DEPENDENCIES: a.txt
+// FILE_DEPENDENCIES: b.txt, c.txt
+// FILE_DEPENDENCIES: /absolute/d.txt
+// RUN: echo %{file_dependencies} | grep 'a.txt'
+// RUN: echo %{file_dependencies} | grep 'b.txt'
+// RUN: echo %{file_dependencies} | grep 'c.txt'
+// RUN: echo %{file_dependencies} | grep '/absolute/d.txt'
diff --git a/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/compile-error.link.fail.cpp b/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/compile-error.link.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/compile-error.link.fail.cpp
@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time.
+
+struct Foo { };
+typedef Foo::x x;
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/link-error.link.fail.cpp b/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/link-error.link.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/link-error.link.fail.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it fails at link time.
+
+extern void this_is_an_undefined_symbol();
+
+int main() {
+    this_is_an_undefined_symbol();
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/link-success.link.fail.cpp b/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/link-success.link.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/link.fail.cpp/link-success.link.fail.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it succeeds to link.
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/compile-error.link.pass.cpp b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/compile-error.link.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/compile-error.link.pass.cpp
@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time.
+
+struct Foo { };
+typedef Foo::x x;
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/link-error.link.pass.cpp b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/link-error.link.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/link-error.link.pass.cpp
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails to link.
+
+extern void this_is_an_undefined_symbol();
+
+int main() {
+    this_is_an_undefined_symbol();
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/link-success.link.pass.cpp b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/link-success.link.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/link-success.link.pass.cpp
@@ -0,0 +1,11 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it succeeds to link.
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/run-error.link.pass.cpp b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/run-error.link.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/link.pass.cpp/run-error.link.pass.cpp
@@ -0,0 +1,14 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it succeeds to link, even though it would have
+// failed at runtime.
+
+int main() {
+    return 1;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/lit.local.cfg b/libcxx/test/libcxx/selftest/newformat/lit.local.cfg
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/lit.local.cfg
@@ -0,0 +1,4 @@
+import libcxx.test.newformat
+
+if not isinstance(config.test_format, libcxx.test.newformat.CxxStandardLibraryTest):
+    config.unsupported = True
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.cpp/compile-error.pass.cpp b/libcxx/test/libcxx/selftest/newformat/pass.cpp/compile-error.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.cpp/compile-error.pass.cpp
@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time
+
+struct Foo { };
+typedef Foo::x x;
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.cpp/link-error.pass.cpp b/libcxx/test/libcxx/selftest/newformat/pass.cpp/link-error.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.cpp/link-error.pass.cpp
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at link-time
+
+extern void this_is_an_undefined_symbol();
+
+int main() {
+    this_is_an_undefined_symbol();
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.cpp/run-error.pass.cpp b/libcxx/test/libcxx/selftest/newformat/pass.cpp/run-error.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.cpp/run-error.pass.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at runtime.
+
+int main() {
+    return 1;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.cpp/run-success.pass.cpp b/libcxx/test/libcxx/selftest/newformat/pass.cpp/run-success.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.cpp/run-success.pass.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes pass if it succeeds at runtime.
+
+int main() {
+    return 0;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.mm/compile-error.pass.mm b/libcxx/test/libcxx/selftest/newformat/pass.mm/compile-error.pass.mm
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.mm/compile-error.pass.mm
@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time
+
+struct Foo { };
+typedef Foo::x x;
+
+int main() { }
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.mm/link-error.pass.mm b/libcxx/test/libcxx/selftest/newformat/pass.mm/link-error.pass.mm
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.mm/link-error.pass.mm
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at link-time
+
+extern void this_is_an_undefined_symbol();
+
+int main() {
+    this_is_an_undefined_symbol();
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.mm/no-arc.pass.mm b/libcxx/test/libcxx/selftest/newformat/pass.mm/no-arc.pass.mm
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.mm/no-arc.pass.mm
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure ARC is not enabled by default in these tests.
+
+#if __has_feature(objc_arc)
+#   error "arc should not be enabled by default"
+#endif
+
+int main() {
+    return 0;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.mm/run-error.pass.mm b/libcxx/test/libcxx/selftest/newformat/pass.mm/run-error.pass.mm
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.mm/run-error.pass.mm
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at runtime.
+
+int main() {
+    return 1;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.mm/run-success.pass.mm b/libcxx/test/libcxx/selftest/newformat/pass.mm/run-success.pass.mm
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.mm/run-success.pass.mm
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes pass if it succeeds at runtime.
+
+int main() {
+    return 0;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/pass.mm/use-objective-cxx.pass.mm b/libcxx/test/libcxx/selftest/newformat/pass.mm/use-objective-cxx.pass.mm
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/pass.mm/use-objective-cxx.pass.mm
@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure we can use Objective C++ features in these tests.
+
+@interface Foo
+@end
+
+int main() {
+    return 0;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/compile-error.run.fail.cpp b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/compile-error.run.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/compile-error.run.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails at compile-time
+
+struct Foo { };
+typedef Foo::x x;
+
+int main() {
+    return 1;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/link-error.run.fail.cpp b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/link-error.run.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/link-error.run.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure that the test DOES NOT pass if it fails at link-time
+
+extern void this_is_an_undefined_symbol();
+
+int main() {
+    this_is_an_undefined_symbol();
+    return 1;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/run-error.run.fail.cpp b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/run-error.run.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/run-error.run.fail.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it fails at runtime.
+
+int main() {
+    return 1;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/run-success.run.fail.cpp b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/run-success.run.fail.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/run.fail.cpp/run-success.run.fail.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it succeeds at runtime.
+
+int main() {
+    return 0;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/sh.cpp/empty.sh.cpp b/libcxx/test/libcxx/selftest/newformat/sh.cpp/empty.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/sh.cpp/empty.sh.cpp
@@ -0,0 +1,11 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it has no 'RUN:' steps
diff --git a/libcxx/test/libcxx/selftest/newformat/sh.cpp/remote-substitutions.sh.cpp b/libcxx/test/libcxx/selftest/newformat/sh.cpp/remote-substitutions.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/sh.cpp/remote-substitutions.sh.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure that test-executables can appear in RUN lines and be executed
+// effectively. This somewhat difficult-to-understand test checks that when
+// we run with a remote executor, test-executables are copied to the remote
+// host and their path is fixed up (directly in the command-line) to their
+// path on the remote host instead of the local host.
+//
+// We also check that the path of test-executables is replaced whether they
+// appear first in the command-line or not.
+
+// FILE_DEPENDENCIES: %t.exe
+// RUN: %{cxx} %{compile_flags} %{link_flags} -o %t.exe %s
+// RUN: %{exec} %t.exe 0
+// RUN: %{exec} ! %t.exe 1
+
+#include <cassert>
+#include <cstdlib>
+
+int main(int argc, char** argv) {
+  assert(argc == 2);
+  int ret = std::atoi(argv[1]);
+  return ret;
+}
diff --git a/libcxx/test/libcxx/selftest/newformat/sh.cpp/run-error.sh.cpp b/libcxx/test/libcxx/selftest/newformat/sh.cpp/run-error.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/sh.cpp/run-error.sh.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// XFAIL: *
+
+// Make sure the test DOES NOT pass if it fails to run
+
+// RUN: exit 1
diff --git a/libcxx/test/libcxx/selftest/newformat/sh.cpp/run-success.sh.cpp b/libcxx/test/libcxx/selftest/newformat/sh.cpp/run-success.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/sh.cpp/run-success.sh.cpp
@@ -0,0 +1,11 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure the test passes if it succeeds to run
+
+// RUN: exit 0
diff --git a/libcxx/test/libcxx/selftest/newformat/sh.cpp/substitutions.sh.cpp b/libcxx/test/libcxx/selftest/newformat/sh.cpp/substitutions.sh.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/libcxx/selftest/newformat/sh.cpp/substitutions.sh.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Make sure we have access to the following substitutions at all times:
+// - %{cxx}
+// - %{compile_flags}
+// - %{link_flags}
+// - %{exec}
+
+// FILE_DEPENDENCIES: %t.exe
+// RUN: %{cxx} %{compile_flags} %{link_flags} -o %t.exe %s
+// RUN: %{exec} %t.exe "HELLO"
+
+#include <cassert>
+#include <string>
+
+int main(int argc, char** argv) {
+  assert(argc == 2);
+
+  std::string arg = argv[1];
+  assert(arg == "HELLO");
+  return 0;
+}
diff --git a/libcxx/test/lit.cfg b/libcxx/test/lit.cfg
--- a/libcxx/test/lit.cfg
+++ b/libcxx/test/lit.cfg
@@ -52,4 +52,9 @@
 configuration = config_module.Configuration(lit_config, config)
 configuration.configure()
 configuration.print_config_info()
-config.test_format = configuration.get_test_format()
+if lit_config.params.get('use_new_format', False):
+    lit_config.note("Using the experimental libc++ testing format")
+    import libcxx.test.newformat
+    config.test_format = libcxx.test.newformat.CxxStandardLibraryTest()
+else:
+    config.test_format = configuration.get_test_format()
diff --git a/libcxx/utils/libcxx/test/newformat.py b/libcxx/utils/libcxx/test/newformat.py
new file mode 100644
--- /dev/null
+++ b/libcxx/utils/libcxx/test/newformat.py
@@ -0,0 +1,233 @@
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+import lit
+import os
+import pipes
+
+class CxxStandardLibraryTest(lit.formats.TestFormat):
+    """
+    Lit test format for the C++ Standard Library conformance test suite.
+
+    This test format is based on top of the ShTest format -- it basically
+    creates a shell script performing the right operations (compile/link/run)
+    based on the extension of the test file it encounters. It supports files
+    with the following extensions:
+
+    FOO.pass.cpp            - Compiles, links and runs successfully
+    FOO.pass.mm             - Same as .pass.cpp, but for Objective-C++
+    FOO.run.fail.cpp        - Compiles and links successfully, but fails at runtime
+    FOO.compile.pass.cpp    - Compiles successfully, link and run not attempted
+    FOO.compile.fail.cpp    - Does not compile successfully (run with clang-verify)
+    FOO.link.pass.cpp       - Compiles and links successfully, run not attempted
+    FOO.link.fail.cpp       - Compiles successfully, but fails to link
+    FOO.sh.cpp              - A builtin lit Shell test
+
+    FOO.fail.cpp            - Does not compile successfully -- run with clang-verify
+                              if any expected-meow appears in the file, otherwise
+                              just test that compilation fails. This is supported
+                              only for backwards compatibility with the test suite
+
+    The test format operates by assuming that each test's configuration provides
+    the following substitutions, which it will reuse in the shell scripts it
+    constructs:
+        %{cxx}           - A command that can be used to invoke the compiler
+        %{compile_flags} - Flags to use when compiling a test case
+        %{link_flags}    - Flags to use when linking a test case
+        %{exec}          - A command to prefix the execution of executables
+
+    Note that when building an executable (as opposed to only compiling a source
+    file), both %{compile_flags} and %{link_flags} will be used in the same
+    command line. In other words, the test format doesn't perform separate
+    compilation and linking steps in this case.
+
+
+    In addition to everything that's supported in Lit ShTests, this test format
+    also understands the following directives inside test files:
+
+        // FILE_DEPENDENCIES: file, directory, /path/to/file
+
+            This directive expresses that the test requires the provided files
+            or directories in order to run. An example is a test that requires
+            some test input stored in a data file. When a test file contains
+            such a directive, this test format will collect them and make them
+            available in a special %{file_dependencies} substitution. The intent
+            is that if one needs to e.g. execute tests on a remote host, the
+            %{exec} substitution could use %{file_dependencies} to know which
+            files and directories to copy to the remote host.
+
+        // ADDITIONAL_COMPILE_FLAGS: flag1, flag2, flag3
+
+            This directive will cause the provided flags to be added to the
+            %{compile_flags} substitution for the test that contains it. This
+            allows adding special compilation flags without having to use a
+            .sh.cpp test, which would be more powerful but perhaps overkill.
+
+    This test format still needs work in the following areas:
+        - It doesn't support the MODULES_DEFINES from the old test format, but
+          that can be achieved easily with ADDITIONAL_COMPILE_FLAGS.
+        - It is unknown how well it works on Windows yet.
+    """
+    def getTestsInDirectory(self, testSuite, pathInSuite, litConfig, localConfig):
+        SUPPORTED_SUFFIXES = ['.pass.cpp', '.run.fail.cpp',
+                              '.pass.mm',
+                              '.compile.pass.cpp', '.compile.fail.cpp',
+                              '.link.pass.cpp', '.link.fail.cpp',
+                              '.sh.cpp',
+                              '.fail.cpp']
+        sourcePath = testSuite.getSourcePath(pathInSuite)
+        for filename in os.listdir(sourcePath):
+            # Ignore dot files and excluded tests.
+            if filename.startswith('.') or filename in localConfig.excludes:
+                continue
+
+            filepath = os.path.join(sourcePath, filename)
+            if not os.path.isdir(filepath):
+                if any([filename.endswith(ext) for ext in SUPPORTED_SUFFIXES]):
+                    yield lit.Test.Test(testSuite, pathInSuite + (filename,), localConfig)
+
+    def _checkSubstitutions(self, substitutions):
+        substitutions = [s for (s, _) in substitutions]
+        for s in ['%{cxx}', '%{compile_flags}', '%{link_flags}', '%{exec}']:
+            assert s in substitutions, "Required substitution {} was not provided".format(s)
+
+    # Determine whether -verify should be used for a given test. We use -verify
+    # if the compiler supports it and there's at least one -verify tag in the
+    # source file.
+    #
+    # This is only supported for backwards compatibility with .fail.cpp tests.
+    def _useVerify(self, test, litConfig):
+        VERIFY_TAGS = (b'expected-note', b'expected-remark',
+                       b'expected-warning', b'expected-error',
+                       b'expected-no-diagnostics')
+        with open(test.getSourcePath(), 'rb') as f:
+            contents = f.read()
+        testContainsTags = any(tag in contents for tag in VERIFY_TAGS)
+
+        command = "echo | %{cxx} -xc++ - -Werror -fsyntax-only -Xclang -verify-ignore-unexpected"
+        result = lit.TestRunner.executeShTest(test, litConfig,
+                                              useExternalSh=True,
+                                              preamble_commands=[command])
+        compilerSupportsVerify = False if result.code == lit.Test.FAIL else True
+        return compilerSupportsVerify and testContainsTags
+
+    def execute(self, test, litConfig):
+        self._checkSubstitutions(test.config.substitutions)
+        VERIFY_FLAGS = '-Xclang -verify -Xclang -verify-ignore-unexpected=note -ferror-limit=0'
+        filename = test.path_in_suite[-1]
+        if filename.endswith('.sh.cpp'):
+            steps = [ ] # The steps are already in the script
+            return self._executeShTest(test, litConfig, steps)
+        elif filename.endswith('.compile.pass.cpp'):
+            steps = [
+                "%dbg(COMPILED WITH) %{cxx} %s %{compile_flags} -fsyntax-only"
+            ]
+            return self._executeShTest(test, litConfig, steps)
+        elif filename.endswith('.compile.fail.cpp'):
+            steps = [
+                "%dbg(COMPILED WITH) %{cxx} %s %{compile_flags} -fsyntax-only " + VERIFY_FLAGS
+            ]
+            return self._executeShTest(test, litConfig, steps)
+        elif filename.endswith('.link.pass.cpp'):
+            steps = [
+                "%dbg(COMPILED WITH) %{cxx} %s %{compile_flags} %{link_flags} -o %t.exe"
+            ]
+            return self._executeShTest(test, litConfig, steps)
+        elif filename.endswith('.link.fail.cpp'):
+            steps = [
+                "%dbg(COMPILED WITH) %{cxx} %s %{compile_flags} -c -o %t.o",
+                "%dbg(LINKED WITH) ! %{cxx} %t.o %{link_flags} -o %t.exe"
+            ]
+            return self._executeShTest(test, litConfig, steps)
+        elif filename.endswith('.run.fail.cpp'):
+            steps = [
+                "%dbg(COMPILED WITH) %{cxx} %s %{compile_flags} %{link_flags} -o %t.exe",
+                "%dbg(EXECUTED AS) %{exec} ! %t.exe"
+            ]
+            return self._executeShTest(test, litConfig, steps, fileDependencies=['%t.exe'])
+        # Make sure to check these ones last, since they will match other
+        # suffixes above too.
+        elif filename.endswith('.pass.cpp') or filename.endswith('.pass.mm'):
+            steps = [
+                "%dbg(COMPILED WITH) %{cxx} %s %{compile_flags} %{link_flags} -o %t.exe",
+                "%dbg(EXECUTED AS) %{exec} %t.exe"
+            ]
+            return self._executeShTest(test, litConfig, steps, fileDependencies=['%t.exe'])
+        # This is the same as .compile.fail.cpp, provided for backwards
+        # compatibility with the test suite.
+        elif filename.endswith('.fail.cpp'):
+            if self._useVerify(test, litConfig):
+                steps = [
+                    "%dbg(COMPILED WITH) %{cxx} %s %{compile_flags} -fsyntax-only " + VERIFY_FLAGS
+                ]
+            else:
+                steps = [
+                    "%dbg(COMPILED WITH) ! %{cxx} %s %{compile_flags} -fsyntax-only"
+                ]
+            return self._executeShTest(test, litConfig, steps)
+        else:
+            return lit.Test.Result(lit.Test.FAIL, "Unknown test suffix for '{}'".format(filename))
+
+    # Utility function to add compile flags in lit.local.cfg files.
+    def addCompileFlags(self, config, *flags):
+        string = ' '.join(flags)
+        config.substitutions = [(s, x + ' ' + string) if s == '%{compile_flags}' else (s, x) for (s, x) in config.substitutions]
+
+    # Modified version of lit.TestRunner.executeShTest to handle custom parsers correctly.
+    def _executeShTest(self, test, litConfig, steps, fileDependencies=None):
+        recursiveExpansionLimit = 10 # TODO: Use the value in litConfig once we set it.
+        if test.config.unsupported:
+            return lit.Test.Result(lit.Test.UNSUPPORTED, 'Test is unsupported')
+
+        additionalCompileFlags = []
+        fileDependencies = fileDependencies or []
+        parsers = [
+            lit.TestRunner.IntegratedTestKeywordParser('FILE_DEPENDENCIES:',
+                                                       lit.TestRunner.ParserKind.LIST,
+                                                       initial_value=fileDependencies),
+            lit.TestRunner.IntegratedTestKeywordParser('ADDITIONAL_COMPILE_FLAGS:',
+                                                       lit.TestRunner.ParserKind.LIST,
+                                                       initial_value=additionalCompileFlags)
+        ]
+
+        script = list(steps)
+        parsed = lit.TestRunner.parseIntegratedTestScript(test, additional_parsers=parsers,
+                                                                require_script=not script)
+        if isinstance(parsed, lit.Test.Result):
+            return parsed
+        script += parsed
+
+        if litConfig.noExecute:
+            return lit.Test.Result(lit.Test.PASS)
+
+        # Add compile flags specified with ADDITIONAL_COMPILE_FLAGS.
+        self.addCompileFlags(test.config, *additionalCompileFlags)
+
+        tmpDir, tmpBase = lit.TestRunner.getTempPaths(test)
+        useExternalSh = True
+        substitutions = lit.TestRunner.getDefaultSubstitutions(test, tmpDir, tmpBase,
+                                                               normalize_slashes=useExternalSh)
+
+        # Perform substitutions inside FILE_DEPENDENCIES lines (or injected dependencies).
+        # This allows using variables like %t in file dependencies. Also note that we really
+        # need to resolve %{file_dependencies} now, because otherwise we won't be able to
+        # make all paths absolute below.
+        fileDependencies = lit.TestRunner.applySubstitutions(fileDependencies, substitutions,
+                                                             recursion_limit=recursiveExpansionLimit)
+
+        # Add the %{file_dependencies} substitution before we perform substitutions
+        # inside the script.
+        testDir = os.path.dirname(test.getSourcePath())
+        fileDependencies = [f if os.path.isabs(f) else os.path.join(testDir, f) for f in fileDependencies]
+        substitutions.append(('%{file_dependencies}', ' '.join(map(pipes.quote, fileDependencies))))
+
+        # Perform substitution in the script itself.
+        script = lit.TestRunner.applySubstitutions(script, substitutions,
+                                                   recursion_limit=recursiveExpansionLimit)
+
+        return lit.TestRunner._runShTest(test, litConfig, useExternalSh, script, tmpBase)
diff --git a/libcxxabi/test/lit.cfg b/libcxxabi/test/lit.cfg
--- a/libcxxabi/test/lit.cfg
+++ b/libcxxabi/test/lit.cfg
@@ -64,4 +64,9 @@
 configuration = config_module.Configuration(lit_config, config)
 configuration.configure()
 configuration.print_config_info()
-config.test_format = configuration.get_test_format()
+if lit_config.params.get('use_new_format', False):
+    lit_config.note("Using the experimental libc++ testing format")
+    import libcxx.test.newformat
+    config.test_format = libcxx.test.newformat.CxxStandardLibraryTest()
+else:
+    config.test_format = configuration.get_test_format()