diff --git a/libc/src/__support/threads/thread.h b/libc/src/__support/threads/thread.h
@@ -11,6 +11,7 @@
 
 #include "src/__support/CPP/StringView.h"
 #include "src/__support/CPP/atomic.h"
+#include "src/__support/CPP/optional.h"
 #include "src/__support/CPP/stringstream.h"
 #include "src/__support/architectures.h"
 
@@ -105,6 +106,30 @@ struct alignas(STACK_ALIGNMENT) ThreadAttributes {
         platform_data(nullptr) {}
 };
 
+using TSSDtor = void(void *);
+
+// Create a new TSS key and associate the |dtor| as the corresponding
+// destructor. Can be used to implement public functions like
+// pthread_key_create.
+cpp::optional<unsigned int> new_tss_key(TSSDtor *dtor);
+
+// Delete the |key|. Can be used to implement public functions like
+// pthread_key_delete.
+//
+// Return true on success, false on failure.
+bool tss_key_delete(unsigned int key);
+
+// Set the value associated with |key| for the current thread. Can be used
+// to implement public functions like pthread_setspecific.
+//
+// Return true on success, false on failure.
+bool set_tss_value(unsigned int key, void *value);
+
+// Return the value associated with |key| for the current thread. Return
+// nullptr if |key| is invalid. Can be used to implement public functions like
+// pthread_getspecific.
+void *get_tss_value(unsigned int key);
+
 struct Thread {
   ThreadAttributes *attrib;
 

diff --git a/libc/src/pthread/CMakeLists.txt b/libc/src/pthread/CMakeLists.txt
@@ -338,3 +338,51 @@ add_entrypoint_object(
     libc.src.__support.CPP.stringstream
     libc.src.__support.threads.thread
 )
+
+add_entrypoint_object(
+  pthread_key_create
+  SRCS
+    pthread_key_create.cpp
+  HDRS
+    pthread_key_create.h
+  DEPENDS
+    libc.include.errno
+    libc.include.pthread
+    libc.src.__support.threads.thread
+)
+
+add_entrypoint_object(
+  pthread_key_delete
+  SRCS
+    pthread_key_delete.cpp
+  HDRS
+    pthread_key_delete.h
+  DEPENDS
+    libc.include.errno
+    libc.include.pthread
+    libc.src.__support.threads.thread
+)
+
+add_entrypoint_object(
+  pthread_getspecific
+  SRCS
+    pthread_getspecific.cpp
+  HDRS
+    pthread_getspecific.h
+  DEPENDS
+    libc.include.errno
+    libc.include.pthread
+    libc.src.__support.threads.thread
+)
+
+add_entrypoint_object(
+  pthread_setspecific
+  SRCS
+    pthread_setspecific.cpp
+  HDRS
+    pthread_setspecific.h
+  DEPENDS
+    libc.include.errno
+    libc.include.pthread
+    libc.src.__support.threads.thread
+)
diff --git a/libc/src/pthread/pthread_getspecific.cpp b/libc/src/pthread/pthread_getspecific.cpp
@@ -0,0 +1,23 @@
+//===-- Linux implementation of the pthread_getspecific function ----------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "pthread_getspecific.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <pthread.h>
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(void *, pthread_getspecific, (pthread_key_t key)) {
+  return get_tss_value(key);
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/pthread/pthread_getspecific.h b/libc/src/pthread/pthread_getspecific.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for pthread_getspecific function --*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_GETSPECIFIC_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_GETSPECIFIC_H
+
+#include <pthread.h>
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+void *pthread_getspecific(pthread_key_t);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_GETSPECIFIC_H
diff --git a/libc/src/pthread/pthread_key_create.cpp b/libc/src/pthread/pthread_key_create.cpp
@@ -0,0 +1,28 @@
+//===-- Implementation of the pthread_key_create --------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "pthread_key_create.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <errno.h>
+#include <pthread.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, pthread_key_create,
+                   (pthread_key_t * key, __pthread_tss_dtor_t dtor)) {
+  auto k = __llvm_libc::new_tss_key(dtor);
+  if (!k)
+    return EINVAL;
+  *key = *k;
+  return 0;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/pthread/pthread_key_create.h b/libc/src/pthread/pthread_key_create.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for pthread_key_create ------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_KEY_CREATE_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_KEY_CREATE_H
+
+#include <pthread.h>
+
+namespace __llvm_libc {
+
+int pthread_key_create(pthread_key_t *key, __pthread_tss_dtor_t dtor);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_KEY_CREATE_H
diff --git a/libc/src/pthread/pthread_key_delete.cpp b/libc/src/pthread/pthread_key_delete.cpp
@@ -0,0 +1,26 @@
+//===-- Implementation of the pthread_key_delete --------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "pthread_key_delete.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <errno.h>
+#include <pthread.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, pthread_key_delete, (pthread_key_t key)) {
+  if (__llvm_libc::tss_key_delete(key))
+    return 0;
+  else
+    return EINVAL;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/pthread/pthread_key_delete.h b/libc/src/pthread/pthread_key_delete.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for pthread_key_delete ------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_KEY_DELETE_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_KEY_DELETE_H
+
+#include <pthread.h>
+
+namespace __llvm_libc {
+
+int pthread_key_delete(pthread_key_t key);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_KEY_DELETE_H
diff --git a/libc/src/pthread/pthread_setspecific.cpp b/libc/src/pthread/pthread_setspecific.cpp
@@ -0,0 +1,27 @@
+//===-- Linux implementation of the pthread_setspecific function ----------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "pthread_setspecific.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <errno.h>
+#include <pthread.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, pthread_setspecific,
+                   (pthread_key_t key, const void *data)) {
+  if (set_tss_value(key, const_cast<void *>(data)))
+    return 0;
+  else
+    return EINVAL;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/pthread/pthread_setspecific.h b/libc/src/pthread/pthread_setspecific.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for pthread_setspecific function --*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_SETSPECIFIC_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_SETSPECIFIC_H
+
+#include <pthread.h>
+
+namespace __llvm_libc {
+
+int pthread_setspecific(pthread_key_t, const void *);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_SETSPECIFIC_H
diff --git a/libc/src/threads/CMakeLists.txt b/libc/src/threads/CMakeLists.txt
@@ -123,6 +123,50 @@ add_entrypoint_object(
     libc.src.__support.threads.mutex
 )
 
+add_entrypoint_object(
+  tss_create
+  SRCS
+    tss_create.cpp
+  HDRS
+    tss_create.h
+  DEPENDS
+    libc.include.threads
+    libc.src.__support.threads.mutex
+)
+
+add_entrypoint_object(
+  tss_delete
+  SRCS
+    tss_delete.cpp
+  HDRS
+    tss_delete.h
+  DEPENDS
+    libc.include.threads
+    libc.src.__support.threads.mutex
+)
+
+add_entrypoint_object(
+  tss_get
+  SRCS
+    tss_get.cpp
+  HDRS
+    tss_get.h
+  DEPENDS
+    libc.include.threads
+    libc.src.__support.threads.mutex
+)
+
+add_entrypoint_object(
+  tss_set
+  SRCS
+    tss_set.cpp
+  HDRS
+    tss_set.h
+  DEPENDS
+    libc.include.threads
+    libc.src.__support.threads.mutex
+)
+
 add_entrypoint_object(
   cnd_init
   ALIAS

diff --git a/libc/src/threads/tss_create.cpp b/libc/src/threads/tss_create.cpp
@@ -0,0 +1,26 @@
+//===-- Implementation of the tss_create ----------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "tss_create.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <threads.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, tss_create, (tss_t * key, tss_dtor_t dtor)) {
+  auto k = __llvm_libc::new_tss_key(dtor);
+  if (!k)
+    return thrd_error;
+  *key = *k;
+  return thrd_success;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/tss_create.h b/libc/src/threads/tss_create.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for tss_create --------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_THREADS_TSS_CREATE_H
+#define LLVM_LIBC_SRC_THREADS_TSS_CREATE_H
+
+#include <threads.h>
+
+namespace __llvm_libc {
+
+int tss_create(tss_t *key, tss_dtor_t dtor);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_TSS_CREATE_H
diff --git a/libc/src/threads/tss_delete.cpp b/libc/src/threads/tss_delete.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of the tss_delete ----------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "tss_delete.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <threads.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(void, tss_delete, (tss_t key)) {
+  __llvm_libc::tss_key_delete(key);
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/tss_delete.h b/libc/src/threads/tss_delete.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for tss_delete --------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_THREADS_TSS_DELETE_H
+#define LLVM_LIBC_SRC_THREADS_TSS_DELETE_H
+
+#include <threads.h>
+
+namespace __llvm_libc {
+
+void tss_delete(tss_t key);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_TSS_DELETE_H
diff --git a/libc/src/threads/tss_get.cpp b/libc/src/threads/tss_get.cpp
@@ -0,0 +1,20 @@
+//===-- Linux implementation of the tss_get function ----------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "tss_get.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <threads.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(void *, tss_get, (tss_t key)) { return get_tss_value(key); }
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/tss_get.h b/libc/src/threads/tss_get.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for tss_get function --------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_THREADS_TSS_GET_H
+#define LLVM_LIBC_SRC_THREADS_TSS_GET_H
+
+#include <pthread.h>
+
+namespace __llvm_libc {
+
+void *tss_get(pthread_key_t);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_TSS_GET_H
diff --git a/libc/src/threads/tss_set.cpp b/libc/src/threads/tss_set.cpp
@@ -0,0 +1,25 @@
+//===-- Linux implementation of the tss_set function ----------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "tss_set.h"
+
+#include "src/__support/common.h"
+#include "src/__support/threads/thread.h"
+
+#include <threads.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, tss_set, (tss_t key, void *data)) {
+  if (set_tss_value(key, data))
+    return thrd_success;
+  else
+    return thrd_error;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/tss_set.h b/libc/src/threads/tss_set.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for tss_set function --------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_THREADS_TSS_SET_H
+#define LLVM_LIBC_SRC_THREADS_TSS_SET_H
+
+#include <threads.h>
+
+namespace __llvm_libc {
+
+int tss_set(tss_t, void *);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_TSS_SET_H
diff --git a/libc/test/integration/src/pthread/CMakeLists.txt b/libc/test/integration/src/pthread/CMakeLists.txt
@@ -91,3 +91,22 @@ add_integration_test(
     libc.src.pthread.pthread_exit
     libc.src.pthread.pthread_join
 )
+
+add_integration_test(
+  pthread_tss_test
+  SUITE
+    libc-pthread-integration-tests
+  SRCS
+    pthread_tss_test.cpp
+  LOADER
+    libc.loader.linux.crt1
+  DEPENDS
+    libc.include.pthread
+    libc.src.pthread.pthread_create
+    libc.src.pthread.pthread_exit
+    libc.src.pthread.pthread_join
+    libc.src.pthread.pthread_key_create
+    libc.src.pthread.pthread_key_delete
+    libc.src.pthread.pthread_getspecific
+    libc.src.pthread.pthread_setspecific
+)
diff --git a/libc/test/integration/src/pthread/pthread_tss_test.cpp b/libc/test/integration/src/pthread/pthread_tss_test.cpp
@@ -0,0 +1,62 @@
+//===-- Tests for TSS API like pthread_setspecific etc. -------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/pthread/pthread_create.h"
+#include "src/pthread/pthread_exit.h"
+#include "src/pthread/pthread_getspecific.h"
+#include "src/pthread/pthread_join.h"
+#include "src/pthread/pthread_key_create.h"
+#include "src/pthread/pthread_key_delete.h"
+#include "src/pthread/pthread_setspecific.h"
+#include "utils/IntegrationTest/test.h"
+
+#include <pthread.h>
+
+static constexpr int THREAD_DATA_INITVAL = 0x1234;
+static constexpr int THREAD_DATA_FINIVAL = 0x4321;
+static constexpr int THREAD_RUN_VAL = 0x600D;
+
+int child_thread_data = THREAD_DATA_INITVAL;
+int main_thread_data = THREAD_DATA_INITVAL;
+
+pthread_key_t key;
+void dtor(void *data) {
+  auto *v = reinterpret_cast<int *>(data);
+  *v = THREAD_DATA_FINIVAL;
+}
+
+void *func(void *obj) {
+  ASSERT_EQ(__llvm_libc::pthread_setspecific(key, &child_thread_data), 0);
+  int *d = reinterpret_cast<int *>(__llvm_libc::pthread_getspecific(key));
+  ASSERT_TRUE(d != nullptr);
+  ASSERT_EQ(&child_thread_data, d);
+  ASSERT_EQ(*d, THREAD_DATA_INITVAL);
+  *reinterpret_cast<int *>(obj) = THREAD_RUN_VAL;
+  return nullptr;
+}
+
+TEST_MAIN() {
+  ASSERT_EQ(__llvm_libc::pthread_key_create(&key, &dtor), 0);
+  ASSERT_EQ(__llvm_libc::pthread_setspecific(key, &main_thread_data), 0);
+  int *d = reinterpret_cast<int *>(__llvm_libc::pthread_getspecific(key));
+  ASSERT_TRUE(d != nullptr);
+  ASSERT_EQ(&main_thread_data, d);
+  ASSERT_EQ(*d, THREAD_DATA_INITVAL);
+
+  pthread_t th;
+  int arg = 0xBAD;
+  ASSERT_EQ(__llvm_libc::pthread_create(&th, nullptr, &func, &arg), 0);
+  void *retval = &child_thread_data; // Init to some non-nullptr val.
+  ASSERT_EQ(__llvm_libc::pthread_join(th, &retval), 0);
+  ASSERT_EQ(retval, nullptr);
+  ASSERT_EQ(arg, THREAD_RUN_VAL);
+  ASSERT_EQ(child_thread_data, THREAD_DATA_FINIVAL);
+
+  ASSERT_EQ(__llvm_libc::pthread_key_delete(key), 0);
+  return 0;
+}
diff --git a/libc/test/integration/src/threads/CMakeLists.txt b/libc/test/integration/src/threads/CMakeLists.txt
@@ -69,6 +69,25 @@ add_integration_test(
     libc.src.threads.thrd_join
 )
 
+add_integration_test(
+  tss_test
+  SUITE
+    libc-threads-integration-tests
+  SRCS
+    tss_test.cpp
+  LOADER
+    libc.loader.linux.crt1
+  DEPENDS
+    libc.include.threads
+    libc.src.threads.thrd_create
+    libc.src.threads.thrd_exit
+    libc.src.threads.thrd_join
+    libc.src.threads.tss_create
+    libc.src.threads.tss_delete
+    libc.src.threads.tss_get
+    libc.src.threads.tss_set
+)
+
 add_integration_test(
   call_once_test
   SUITE

diff --git a/libc/test/integration/src/threads/tss_test.cpp b/libc/test/integration/src/threads/tss_test.cpp
@@ -0,0 +1,63 @@
+//===-- Tests for TSS API like tss_set, tss_get etc. ----------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/threads/thrd_create.h"
+#include "src/threads/thrd_exit.h"
+#include "src/threads/thrd_join.h"
+#include "src/threads/tss_create.h"
+#include "src/threads/tss_delete.h"
+#include "src/threads/tss_get.h"
+#include "src/threads/tss_set.h"
+#include "utils/IntegrationTest/test.h"
+
+#include <threads.h>
+
+static constexpr int THREAD_DATA_INITVAL = 0x1234;
+static constexpr int THREAD_DATA_FINIVAL = 0x4321;
+static constexpr int THREAD_RUN_VAL = 0x600D;
+
+int child_thread_data = THREAD_DATA_INITVAL;
+int main_thread_data = THREAD_DATA_INITVAL;
+
+tss_t key;
+void dtor(void *data) {
+  auto *v = reinterpret_cast<int *>(data);
+  *v = THREAD_DATA_FINIVAL;
+}
+
+int func(void *obj) {
+  ASSERT_EQ(__llvm_libc::tss_set(key, &child_thread_data), thrd_success);
+  int *d = reinterpret_cast<int *>(__llvm_libc::tss_get(key));
+  ASSERT_TRUE(d != nullptr);
+  ASSERT_EQ(&child_thread_data, d);
+  ASSERT_EQ(*d, THREAD_DATA_INITVAL);
+  *reinterpret_cast<int *>(obj) = THREAD_RUN_VAL;
+  return 0;
+}
+
+TEST_MAIN() {
+  ASSERT_EQ(__llvm_libc::tss_create(&key, &dtor), thrd_success);
+  ASSERT_EQ(__llvm_libc::tss_set(key, &main_thread_data), thrd_success);
+  int *d = reinterpret_cast<int *>(__llvm_libc::tss_get(key));
+  ASSERT_TRUE(d != nullptr);
+  ASSERT_EQ(&main_thread_data, d);
+  ASSERT_EQ(*d, THREAD_DATA_INITVAL);
+
+  thrd_t th;
+  int arg = 0xBAD;
+  ASSERT_EQ(__llvm_libc::thrd_create(&th, &func, &arg), thrd_success);
+  int retval = THREAD_DATA_INITVAL; // Init to some non-zero val.
+  ASSERT_EQ(__llvm_libc::thrd_join(th, &retval), thrd_success);
+  ASSERT_EQ(retval, 0);
+  ASSERT_EQ(arg, THREAD_RUN_VAL);
+  ASSERT_EQ(child_thread_data, THREAD_DATA_FINIVAL);
+
+  __llvm_libc::tss_delete(key);
+
+  return 0;
+}