diff --git a/libcxx/test/libcxx/thread/thread.mutex/thread_safety_annotations_not_enabled.pass.cpp b/libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_annotations_not_enabled.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/thread/thread.mutex/thread_safety_annotations_not_enabled.pass.cpp
rename to libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_annotations_not_enabled.pass.cpp
diff --git a/libcxx/test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp b/libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_lock_guard.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp
rename to libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_lock_guard.pass.cpp
diff --git a/libcxx/test/libcxx/thread/thread.mutex/thread_safety_lock_unlock.pass.cpp b/libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_lock_unlock.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/thread/thread.mutex/thread_safety_lock_unlock.pass.cpp
rename to libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_lock_unlock.pass.cpp
diff --git a/libcxx/test/libcxx/thread/thread.mutex/thread_safety_missing_unlock.verify.cpp b/libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_missing_unlock.verify.cpp
similarity index 100%
rename from libcxx/test/libcxx/thread/thread.mutex/thread_safety_missing_unlock.verify.cpp
rename to libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_missing_unlock.verify.cpp
diff --git a/libcxx/test/libcxx/thread/thread.mutex/thread_safety_requires_capability.pass.cpp b/libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_requires_capability.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/thread/thread.mutex/thread_safety_requires_capability.pass.cpp
rename to libcxx/test/extensions/clang/thread/thread.mutex/thread_safety_requires_capability.pass.cpp
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/test.dat b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.cons/test.dat
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/test.dat
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.cons/test.dat
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/test.dat b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.members/test.dat
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/test.dat
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ifstream.members/test.dat
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp b/libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp
rename to libcxx/test/extensions/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp
diff --git a/libcxx/test/libcxx/iterators/stream.iterators/ostreambuf.iterator/ostreambuf.iter.ops/failed.pass.cpp b/libcxx/test/extensions/libcxx/iterators/stream.iterators/ostreambuf.iterator/ostreambuf.iter.ops/failed.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/iterators/stream.iterators/ostreambuf.iterator/ostreambuf.iter.ops/failed.pass.cpp
rename to libcxx/test/extensions/libcxx/iterators/stream.iterators/ostreambuf.iterator/ostreambuf.iter.ops/failed.pass.cpp
diff --git a/libcxx/test/libcxx/odr_signature.exceptions.sh.cpp b/libcxx/test/extensions/libcxx/odr_signature.exceptions.sh.cpp
similarity index 100%
rename from libcxx/test/libcxx/odr_signature.exceptions.sh.cpp
rename to libcxx/test/extensions/libcxx/odr_signature.exceptions.sh.cpp
diff --git a/libcxx/test/libcxx/odr_signature.hardening.sh.cpp b/libcxx/test/extensions/libcxx/odr_signature.hardening.sh.cpp
similarity index 100%
rename from libcxx/test/libcxx/odr_signature.hardening.sh.cpp
rename to libcxx/test/extensions/libcxx/odr_signature.hardening.sh.cpp
diff --git a/libcxx/test/libcxx/strings/basic.string/string.capacity/PR53170.pass.cpp b/libcxx/test/extensions/libcxx/strings/basic.string/string.capacity/PR53170.pass.cpp
similarity index 100%
rename from libcxx/test/libcxx/strings/basic.string/string.capacity/PR53170.pass.cpp
rename to libcxx/test/extensions/libcxx/strings/basic.string/string.capacity/PR53170.pass.cpp
diff --git a/libcxx/test/libcxx/xopen_source.gen.py b/libcxx/test/extensions/posix/xopen_source.gen.py
similarity index 100%
rename from libcxx/test/libcxx/xopen_source.gen.py
rename to libcxx/test/extensions/posix/xopen_source.gen.py