diff --git a/libcxx/include/__stop_token/stop_callback.h b/libcxx/include/__stop_token/stop_callback.h
--- a/libcxx/include/__stop_token/stop_callback.h
+++ b/libcxx/include/__stop_token/stop_callback.h
@@ -28,7 +28,7 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
+#if _LIBCPP_STD_VER >= 20 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
 
 template <class _Callback>
 class _LIBCPP_AVAILABILITY_SYNC stop_callback : private __stop_callback_base {
@@ -96,4 +96,4 @@
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP___STOP_TOKEN_STOP_TOKEN_H
+#endif // _LIBCPP_STD_VER >= 20 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
diff --git a/libcxx/include/__stop_token/stop_source.h b/libcxx/include/__stop_token/stop_source.h
--- a/libcxx/include/__stop_token/stop_source.h
+++ b/libcxx/include/__stop_token/stop_source.h
@@ -23,7 +23,7 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
+#if _LIBCPP_STD_VER >= 20 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
 
 struct nostopstate_t {
   explicit nostopstate_t() = default;
@@ -89,4 +89,4 @@
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP___STOP_TOKEN_STOP_SOURCE_H
+#endif // _LIBCPP_STD_VER >= 20 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
diff --git a/libcxx/include/__stop_token/stop_token.h b/libcxx/include/__stop_token/stop_token.h
--- a/libcxx/include/__stop_token/stop_token.h
+++ b/libcxx/include/__stop_token/stop_token.h
@@ -21,7 +21,7 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
+#if _LIBCPP_STD_VER >= 20 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
 
 class _LIBCPP_AVAILABILITY_SYNC stop_token {
 public:
@@ -57,7 +57,7 @@
   _LIBCPP_HIDE_FROM_ABI explicit stop_token(const __intrusive_shared_ptr<__stop_state>& __state) : __state_(__state) {}
 };
 
-#endif // _LIBCPP_STD_VER >= 20
+#endif // _LIBCPP_STD_VER >= 20 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/nostopstate/cons.default.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/nostopstate/cons.default.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/nostopstate/cons.default.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/nostopstate/cons.default.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
 // struct nostopstate_t {
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.const.token.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.const.token.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.const.token.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.const.token.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.rvalue.token.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.rvalue.token.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.rvalue.token.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopcallback/cons.rvalue.token.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopcallback/copy.move.compile.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopcallback/copy.move.compile.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopcallback/copy.move.compile.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopcallback/copy.move.compile.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopcallback/ctad.compile.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopcallback/ctad.compile.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopcallback/ctad.compile.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopcallback/ctad.compile.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopcallback/dtor.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopcallback/dtor.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopcallback/dtor.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopcallback/dtor.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopcallback/typedef.compile.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopcallback/typedef.compile.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopcallback/typedef.compile.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopcallback/typedef.compile.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
 // using callback_type = _Callback;
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/assign.copy.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/assign.copy.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/assign.copy.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/assign.copy.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.copy.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.copy.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.copy.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.copy.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.default.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.default.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.default.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.default.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.move.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.move.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.move.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.move.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.nostopstate.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.nostopstate.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.nostopstate.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/cons.nostopstate.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/equals.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/equals.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/equals.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/equals.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/get_token.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/get_token.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/get_token.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/get_token.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/move.copy.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/move.copy.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/move.copy.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/move.copy.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/nodiscard.verify.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/nodiscard.verify.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/nodiscard.verify.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/nodiscard.verify.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/request_stop.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/request_stop.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/request_stop.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/request_stop.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_possible.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_possible.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_possible.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_possible.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_requested.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_requested.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_requested.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/stop_requested.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.free.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.free.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.free.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.free.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.member.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.member.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.member.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stopsource/swap.member.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.copy.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.copy.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.copy.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.copy.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.move.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.move.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.move.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/assign.move.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.copy.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.copy.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.copy.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.copy.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.default.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.default.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.default.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.default.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.move.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.move.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.move.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/cons.move.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/equals.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/equals.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/equals.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/equals.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/nodiscard.verify.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/nodiscard.verify.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/nodiscard.verify.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/nodiscard.verify.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_possible.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_possible.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_possible.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_possible.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_requested.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_requested.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_requested.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_requested.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.free.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.free.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.free.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.free.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
 
diff --git a/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.member.pass.cpp b/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.member.pass.cpp
--- a/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.member.pass.cpp
+++ b/libcxx/test/std/thread/thread.stoptoken/stoptoken/swap.member.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: no-threads
+// UNSUPPORTED: !c++experimental
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing