diff --git a/core/libs/prx/libc/CMakeLists.txt b/core/libs/prx/libc/CMakeLists.txt
index d8f9c928da..a3b839e5b8 100644
--- a/core/libs/prx/libc/CMakeLists.txt
+++ b/core/libs/prx/libc/CMakeLists.txt
@@ -743,6 +743,16 @@ if(BUILD_TESTING)
         set_tests_properties(guest_qsort PROPERTIES ENVIRONMENT_MODIFICATION
             "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
     endif()
+    add_test_executable(guest_cxa_guard_tests ${LIBS_INCLUDE_DIR}/tests/GuestCxaGuard.cpp)
+    target_include_directories(guest_cxa_guard_tests PRIVATE ${LIBS_INCLUDE_DIR})
+    target_link_libraries(guest_cxa_guard_tests PRIVATE libc)
+    configure_windows_unwind(guest_cxa_guard_tests)
+    add_test(NAME guest_cxa_guard COMMAND guest_cxa_guard_tests)
+    set_tests_properties(guest_cxa_guard PROPERTIES TIMEOUT 20)
+    if(WIN32)
+        set_tests_properties(guest_cxa_guard PROPERTIES ENVIRONMENT_MODIFICATION
+            "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
+    endif()
     add_test_executable(guest_strftime_tests ${LIBS_INCLUDE_DIR}/tests/GuestStrftime.cpp)
     target_include_directories(guest_strftime_tests PRIVATE ${LIBS_INCLUDE_DIR})
     target_link_libraries(guest_strftime_tests PRIVATE libc)
diff --git a/core/libs/tests/GuestCxaGuard.cpp b/core/libs/tests/GuestCxaGuard.cpp
new file mode 100644
index 0000000000..5846411155
--- /dev/null
+++ b/core/libs/tests/GuestCxaGuard.cpp
@@ -0,0 +1,104 @@
+#include "prx/libc/include/Api.hpp"
+
+#include <atomic>
+#include <chrono>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <thread>
+
+static void RequireAt(bool value, int line) {
+    if (!value) {
+        std::fprintf(stderr, "cxa guard check failed at line %d\n", line);
+        std::abort();
+    }
+}
+#define Require(value) RequireAt((value), __LINE__)
+
+static bool Initialized(const std::uint64_t& guard) {
+    return (guard & 1) != 0;
+}
+
+static void WaitForStartAt(const std::atomic<bool>& started, int line) {
+    const auto deadline = std::chrono::steady_clock::now() + std::chrono::seconds(5);
+    while (!started && std::chrono::steady_clock::now() < deadline) std::this_thread::sleep_for(std::chrono::milliseconds(1));
+    RequireAt(started, line);
+}
+#define WaitForStart(started) WaitForStartAt((started), __LINE__)
+
+int main() {
+    {
+        std::uint64_t guard = 0;
+        Require(__cxa_guard_acquire_nid_postfix(&guard) != 0);
+        Require(!Initialized(guard));
+        __cxa_guard_release_nid_postfix(&guard);
+        Require(Initialized(guard));
+        Require(__cxa_guard_acquire_nid_postfix(&guard) == 0);
+        Require(Initialized(guard));
+    }
+
+    {
+        std::uint64_t guard = 0;
+        Require(__cxa_guard_acquire_nid_postfix(&guard) != 0);
+        __cxa_guard_abort_nid_postfix(&guard);
+        Require(!Initialized(guard));
+        Require(__cxa_guard_acquire_nid_postfix(&guard) != 0);
+        __cxa_guard_release_nid_postfix(&guard);
+        Require(Initialized(guard));
+        Require(__cxa_guard_acquire_nid_postfix(&guard) == 0);
+    }
+
+    {
+        std::uint64_t outer = 0;
+        std::uint64_t inner = 0;
+        Require(__cxa_guard_acquire_nid_postfix(&outer) != 0);
+        Require(__cxa_guard_acquire_nid_postfix(&inner) != 0);
+        __cxa_guard_release_nid_postfix(&inner);
+        Require(Initialized(inner) && !Initialized(outer));
+        __cxa_guard_release_nid_postfix(&outer);
+        Require(Initialized(outer));
+    }
+
+    {
+        std::uint64_t guard = 0;
+        Require(__cxa_guard_acquire_nid_postfix(&guard) != 0);
+        std::atomic<bool> started{false};
+        std::atomic<bool> returned{false};
+        std::atomic<int> result{-1};
+        std::thread waiter([&] {
+            started = true;
+            result = __cxa_guard_acquire_nid_postfix(&guard);
+            returned = true;
+        });
+        WaitForStart(started);
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+        Require(!returned);
+        __cxa_guard_release_nid_postfix(&guard);
+        waiter.join();
+        Require(returned && result == 0);
+        Require(Initialized(guard));
+    }
+
+    {
+        std::uint64_t guard = 0;
+        Require(__cxa_guard_acquire_nid_postfix(&guard) != 0);
+        std::atomic<bool> started{false};
+        std::atomic<bool> returned{false};
+        std::atomic<int> result{-1};
+        std::thread waiter([&] {
+            started = true;
+            result = __cxa_guard_acquire_nid_postfix(&guard);
+            returned = true;
+            if (result != 0) __cxa_guard_release_nid_postfix(&guard);
+        });
+        WaitForStart(started);
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+        Require(!returned);
+        __cxa_guard_abort_nid_postfix(&guard);
+        waiter.join();
+        Require(returned && result != 0);
+        Require(Initialized(guard));
+    }
+
+    return 0;
+}