[libc] Mass replace enclosing namespace (#67032)

This is step 4 of
https://discourse.llvm.org/t/rfc-customizable-namespace-to-allow-testing-the-libc-when-the-system-libc-is-also-llvms-libc/73079

43 files changed, 104 insertions, 104 deletions

diff --git a/libc/src/threads/call_once.cpp b/libc/src/threads/call_once.cpp
index 67ab34509a4c..2d91094b1209 100644
--- a/libc/src/threads/call_once.cpp
+++ b/libc/src/threads/call_once.cpp
@@ -12,7 +12,7 @@
 
 #include <threads.h> // For once_flag and __call_once_func_t definitions.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(void, call_once,
                    (once_flag * flag, __call_once_func_t func)) {
@@ -20,4 +20,4 @@ LLVM_LIBC_FUNCTION(void, call_once,
            reinterpret_cast<CallOnceCallback *>(func));
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/call_once.h b/libc/src/threads/call_once.h
index c1e1a71da2d5..186d63cecdbd 100644
--- a/libc/src/threads/call_once.h
+++ b/libc/src/threads/call_once.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 void call_once(once_flag *flag, __call_once_func_t func);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_CALL_ONCE_H
diff --git a/libc/src/threads/cnd_broadcast.h b/libc/src/threads/cnd_broadcast.h
index fd021956b7f6..4e996f22748f 100644
--- a/libc/src/threads/cnd_broadcast.h
+++ b/libc/src/threads/cnd_broadcast.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int cnd_broadcast(cnd_t *cond);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_CND_BROADCAST_H
diff --git a/libc/src/threads/cnd_destroy.h b/libc/src/threads/cnd_destroy.h
index 3400257529e3..d102e7b83e7b 100644
--- a/libc/src/threads/cnd_destroy.h
+++ b/libc/src/threads/cnd_destroy.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 void cnd_destroy(cnd_t *cond);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_CND_DESTROY_H
diff --git a/libc/src/threads/cnd_init.h b/libc/src/threads/cnd_init.h
index 826564b04986..c4fc02f5f9e7 100644
--- a/libc/src/threads/cnd_init.h
+++ b/libc/src/threads/cnd_init.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int cnd_init(cnd_t *cond);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_CND_INIT_H
diff --git a/libc/src/threads/cnd_signal.h b/libc/src/threads/cnd_signal.h
index ec2a97721997..4c60a9295299 100644
--- a/libc/src/threads/cnd_signal.h
+++ b/libc/src/threads/cnd_signal.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int cnd_signal(cnd_t *cond);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_CND_SIGNAL_H
diff --git a/libc/src/threads/cnd_wait.h b/libc/src/threads/cnd_wait.h
index 812e70425060..5d2cdbb68c78 100644
--- a/libc/src/threads/cnd_wait.h
+++ b/libc/src/threads/cnd_wait.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int cnd_wait(cnd_t *cond, mtx_t *mutex);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_CND_WAIT_H
diff --git a/libc/src/threads/linux/CndVar.h b/libc/src/threads/linux/CndVar.h
index 535f7299fcc0..b4afdef9f9eb 100644
--- a/libc/src/threads/linux/CndVar.h
+++ b/libc/src/threads/linux/CndVar.h
@@ -19,7 +19,7 @@
 #include <sys/syscall.h> // For syscall numbers.
 #include <threads.h>     // For values like thrd_success etc.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 struct CndVar {
   enum CndWaiterStatus : uint32_t {
@@ -84,8 +84,8 @@ struct CndVar {
       }
     }
 
-    __llvm_libc::syscall_impl<long>(FUTEX_SYSCALL_ID, &waiter.futex_word.val,
-                                    FUTEX_WAIT, WS_Waiting, 0, 0, 0);
+    LIBC_NAMESPACE::syscall_impl<long>(FUTEX_SYSCALL_ID, &waiter.futex_word.val,
+                                       FUTEX_WAIT, WS_Waiting, 0, 0, 0);
 
     // At this point, if locking |m| fails, we can simply return as the
     // queued up waiter would have been removed from the queue.
@@ -109,7 +109,7 @@ struct CndVar {
 
     qmtx.futex_word = FutexWordType(Mutex::LockState::Free);
 
-    __llvm_libc::syscall_impl<long>(
+    LIBC_NAMESPACE::syscall_impl<long>(
         FUTEX_SYSCALL_ID, &qmtx.futex_word.val, FUTEX_WAKE_OP, 1, 1,
         &first->futex_word.val,
         FUTEX_OP(FUTEX_OP_SET, WS_Signalled, FUTEX_OP_CMP_EQ, WS_Waiting));
@@ -126,7 +126,7 @@ struct CndVar {
       // atomically update the waiter status to WS_Signalled before waking
       // up the waiter. A dummy location is used for the other futex of
       // FUTEX_WAKE_OP.
-      __llvm_libc::syscall_impl<long>(
+      LIBC_NAMESPACE::syscall_impl<long>(
           FUTEX_SYSCALL_ID, &dummy_futex_word, FUTEX_WAKE_OP, 1, 1,
           &waiter->futex_word.val,
           FUTEX_OP(FUTEX_OP_SET, WS_Signalled, FUTEX_OP_CMP_EQ, WS_Waiting));
@@ -141,6 +141,6 @@ static_assert(sizeof(CndVar) == sizeof(cnd_t),
               "internal representation of condition variable and the public "
               "cnd_t type.");
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_LINUX_CNDVAR_H
diff --git a/libc/src/threads/linux/Futex.h b/libc/src/threads/linux/Futex.h
index 53e2858d5747..4b426ac51ad1 100644
--- a/libc/src/threads/linux/Futex.h
+++ b/libc/src/threads/linux/Futex.h
@@ -11,7 +11,7 @@
 
 #include "src/__support/macros/properties/architectures.h" // Architecture macros
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 #if (defined(LIBC_TARGET_ARCH_IS_AARCH64) ||                                   \
      defined(LIBC_TARGET_ARCH_IS_X86_64))
@@ -27,6 +27,6 @@ static_assert(sizeof(FutexWordType) == 4,
 #error "Futex word base type not defined for the target architecture."
 #endif
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_LINUX_FUTEX_H
diff --git a/libc/src/threads/linux/call_once.cpp b/libc/src/threads/linux/call_once.cpp
index a3c0131ff78f..5cdd8ebfd190 100644
--- a/libc/src/threads/linux/call_once.cpp
+++ b/libc/src/threads/linux/call_once.cpp
@@ -19,7 +19,7 @@
 #include <sys/syscall.h> // For syscall numbers.
 #include <threads.h>     // For call_once related type definition.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 static constexpr FutexWordType START = 0x11;
 static constexpr FutexWordType WAITING = 0x22;
@@ -46,10 +46,10 @@ LLVM_LIBC_FUNCTION(void, call_once,
     func();
     auto status = futex_word->exchange(FINISH);
     if (status == WAITING) {
-      __llvm_libc::syscall_impl(FUTEX_SYSCALL_ID, &futex_word->val,
-                                FUTEX_WAKE_PRIVATE,
-                                INT_MAX, // Wake all waiters.
-                                0, 0, 0);
+      LIBC_NAMESPACE::syscall_impl(FUTEX_SYSCALL_ID, &futex_word->val,
+                                   FUTEX_WAKE_PRIVATE,
+                                   INT_MAX, // Wake all waiters.
+                                   0, 0, 0);
     }
     return;
   }
@@ -57,11 +57,11 @@ LLVM_LIBC_FUNCTION(void, call_once,
   FutexWordType status = START;
   if (futex_word->compare_exchange_strong(status, WAITING) ||
       status == WAITING) {
-    __llvm_libc::syscall_impl(
+    LIBC_NAMESPACE::syscall_impl(
         FUTEX_SYSCALL_ID, &futex_word->val, FUTEX_WAIT_PRIVATE,
         WAITING, // Block only if status is still |WAITING|.
         0, 0, 0);
   }
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/linux/cnd_broadcast.cpp b/libc/src/threads/linux/cnd_broadcast.cpp
index 7b7c8f3b1cfd..180ac6d68ee8 100644
--- a/libc/src/threads/linux/cnd_broadcast.cpp
+++ b/libc/src/threads/linux/cnd_broadcast.cpp
@@ -11,11 +11,11 @@
 #include "src/threads/cnd_broadcast.h"
 #include "src/__support/common.h"
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(int, cnd_broadcast, (cnd_t * cond)) {
   CndVar *cndvar = reinterpret_cast<CndVar *>(cond);
   return cndvar->broadcast();
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/linux/cnd_destroy.cpp b/libc/src/threads/linux/cnd_destroy.cpp
index 947c5be0bcd8..08eb3a1057b1 100644
--- a/libc/src/threads/linux/cnd_destroy.cpp
+++ b/libc/src/threads/linux/cnd_destroy.cpp
@@ -11,11 +11,11 @@
 #include "src/threads/cnd_destroy.h"
 #include "src/__support/common.h"
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(void, cnd_destroy, (cnd_t * cond)) {
   CndVar *cndvar = reinterpret_cast<CndVar *>(cond);
   CndVar::destroy(cndvar);
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/linux/cnd_init.cpp b/libc/src/threads/linux/cnd_init.cpp
index 5e3156de9370..5e3f360b1d2b 100644
--- a/libc/src/threads/linux/cnd_init.cpp
+++ b/libc/src/threads/linux/cnd_init.cpp
@@ -11,11 +11,11 @@
 #include "src/threads/cnd_init.h"
 #include "src/__support/common.h"
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(int, cnd_init, (cnd_t * cond)) {
   CndVar *cndvar = reinterpret_cast<CndVar *>(cond);
   return CndVar::init(cndvar);
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/linux/cnd_signal.cpp b/libc/src/threads/linux/cnd_signal.cpp
index 6099b13ed987..dba01abdefbc 100644
--- a/libc/src/threads/linux/cnd_signal.cpp
+++ b/libc/src/threads/linux/cnd_signal.cpp
@@ -11,11 +11,11 @@
 #include "src/threads/cnd_signal.h"
 #include "src/__support/common.h"
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(int, cnd_signal, (cnd_t * cond)) {
   CndVar *cndvar = reinterpret_cast<CndVar *>(cond);
   return cndvar->notify_one();
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/linux/cnd_wait.cpp b/libc/src/threads/linux/cnd_wait.cpp
index 5c0aed7be76d..db3d7f1436eb 100644
--- a/libc/src/threads/linux/cnd_wait.cpp
+++ b/libc/src/threads/linux/cnd_wait.cpp
@@ -12,7 +12,7 @@
 #include "src/__support/threads/mutex.h"
 #include "src/threads/cnd_wait.h"
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(int, cnd_wait, (cnd_t * cond, mtx_t *mtx)) {
   CndVar *cndvar = reinterpret_cast<CndVar *>(cond);
@@ -20,4 +20,4 @@ LLVM_LIBC_FUNCTION(int, cnd_wait, (cnd_t * cond, mtx_t *mtx)) {
   return cndvar->wait(mutex);
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/mtx_destroy.cpp b/libc/src/threads/mtx_destroy.cpp
index 64327003bfc5..5ee4777f5b2c 100644
--- a/libc/src/threads/mtx_destroy.cpp
+++ b/libc/src/threads/mtx_destroy.cpp
@@ -12,8 +12,8 @@
 
 #include <threads.h> // For mtx_t definition.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(void, mtx_destroy, (mtx_t *)) {}
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/mtx_destroy.h b/libc/src/threads/mtx_destroy.h
index 353bc27453ba..1abf5d572f5d 100644
--- a/libc/src/threads/mtx_destroy.h
+++ b/libc/src/threads/mtx_destroy.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 void mtx_destroy(mtx_t *mutex);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_MTX_DESTROY_H
diff --git a/libc/src/threads/mtx_init.cpp b/libc/src/threads/mtx_init.cpp
index 188209c9d371..74d08d33b116 100644
--- a/libc/src/threads/mtx_init.cpp
+++ b/libc/src/threads/mtx_init.cpp
@@ -12,7 +12,7 @@
 
 #include <threads.h> // For mtx_t definition.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 static_assert(sizeof(Mutex) <= sizeof(mtx_t),
               "The public mtx_t type cannot accommodate the internal mutex "
@@ -24,4 +24,4 @@ LLVM_LIBC_FUNCTION(int, mtx_init, (mtx_t * m, int type)) {
   return err == MutexError::NONE ? thrd_success : thrd_error;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/mtx_init.h b/libc/src/threads/mtx_init.h
index 8fcaa42a2307..69294d796666 100644
--- a/libc/src/threads/mtx_init.h
+++ b/libc/src/threads/mtx_init.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int mtx_init(mtx_t *mutex, int type);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_MTX_INIT_H
diff --git a/libc/src/threads/mtx_lock.cpp b/libc/src/threads/mtx_lock.cpp
index 58379f6f9d0f..013a88a8e02b 100644
--- a/libc/src/threads/mtx_lock.cpp
+++ b/libc/src/threads/mtx_lock.cpp
@@ -12,7 +12,7 @@
 
 #include <threads.h> // For mtx_t definition.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 // The implementation currently handles only plain mutexes.
 LLVM_LIBC_FUNCTION(int, mtx_lock, (mtx_t * mutex)) {
@@ -21,4 +21,4 @@ LLVM_LIBC_FUNCTION(int, mtx_lock, (mtx_t * mutex)) {
   return err == MutexError::NONE ? thrd_success : thrd_error;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/mtx_lock.h b/libc/src/threads/mtx_lock.h
index df3ec0dccbdb..15c9e1a12545 100644
--- a/libc/src/threads/mtx_lock.h
+++ b/libc/src/threads/mtx_lock.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int mtx_lock(mtx_t *mutex);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_MTX_LOCK_H
diff --git a/libc/src/threads/mtx_unlock.cpp b/libc/src/threads/mtx_unlock.cpp
index f5c6a136d9db..a72ee4427c5a 100644
--- a/libc/src/threads/mtx_unlock.cpp
+++ b/libc/src/threads/mtx_unlock.cpp
@@ -12,7 +12,7 @@
 
 #include <threads.h> // For mtx_t definition.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 // The implementation currently handles only plain mutexes.
 LLVM_LIBC_FUNCTION(int, mtx_unlock, (mtx_t * mutex)) {
@@ -21,4 +21,4 @@ LLVM_LIBC_FUNCTION(int, mtx_unlock, (mtx_t * mutex)) {
   return err == MutexError::NONE ? thrd_success : thrd_error;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/mtx_unlock.h b/libc/src/threads/mtx_unlock.h
index b58df6392265..54fb034a04a2 100644
--- a/libc/src/threads/mtx_unlock.h
+++ b/libc/src/threads/mtx_unlock.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int mtx_unlock(mtx_t *mutex);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_MTX_UNLOCK_H
diff --git a/libc/src/threads/thrd_create.cpp b/libc/src/threads/thrd_create.cpp
index 8ec3cf1c3fcd..06cba84eb864 100644
--- a/libc/src/threads/thrd_create.cpp
+++ b/libc/src/threads/thrd_create.cpp
@@ -13,14 +13,14 @@
 #include <errno.h>
 #include <threads.h> // For thrd_* type definitions.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
-static_assert(sizeof(thrd_t) == sizeof(__llvm_libc::Thread),
+static_assert(sizeof(thrd_t) == sizeof(LIBC_NAMESPACE::Thread),
               "Mismatch between thrd_t and internal Thread.");
 
 LLVM_LIBC_FUNCTION(int, thrd_create,
                    (thrd_t * th, thrd_start_t func, void *arg)) {
-  auto *thread = reinterpret_cast<__llvm_libc::Thread *>(th);
+  auto *thread = reinterpret_cast<LIBC_NAMESPACE::Thread *>(th);
   int result = thread->run(func, arg);
   if (result == 0)
     return thrd_success;
@@ -30,4 +30,4 @@ LLVM_LIBC_FUNCTION(int, thrd_create,
     return thrd_error;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/thrd_create.h b/libc/src/threads/thrd_create.h
index 9ed19c48c0a4..0efa6f58c47e 100644
--- a/libc/src/threads/thrd_create.h
+++ b/libc/src/threads/thrd_create.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int thrd_create(thrd_t *thread, thrd_start_t func, void *arg);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_THRD_CREATE_H
diff --git a/libc/src/threads/thrd_current.cpp b/libc/src/threads/thrd_current.cpp
index e8afd7bf6c49..b5ea0432aa52 100644
--- a/libc/src/threads/thrd_current.cpp
+++ b/libc/src/threads/thrd_current.cpp
@@ -12,9 +12,9 @@
 
 #include <threads.h> // For thrd_* type definitions.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
-static_assert(sizeof(thrd_t) == sizeof(__llvm_libc::Thread),
+static_assert(sizeof(thrd_t) == sizeof(LIBC_NAMESPACE::Thread),
               "Mismatch between thrd_t and internal Thread.");
 
 LLVM_LIBC_FUNCTION(thrd_t, thrd_current, ()) {
@@ -23,4 +23,4 @@ LLVM_LIBC_FUNCTION(thrd_t, thrd_current, ()) {
   return th;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/thrd_current.h b/libc/src/threads/thrd_current.h
index 338a16dc56e9..2125729ccffe 100644
--- a/libc/src/threads/thrd_current.h
+++ b/libc/src/threads/thrd_current.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 thrd_t thrd_current();
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_THRD_CURRENT_H
diff --git a/libc/src/threads/thrd_detach.cpp b/libc/src/threads/thrd_detach.cpp
index 20c6540faa17..17731c638bd5 100644
--- a/libc/src/threads/thrd_detach.cpp
+++ b/libc/src/threads/thrd_detach.cpp
@@ -12,9 +12,9 @@
 
 #include <threads.h> // For thrd_* type definitions.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
-static_assert(sizeof(thrd_t) == sizeof(__llvm_libc::Thread),
+static_assert(sizeof(thrd_t) == sizeof(LIBC_NAMESPACE::Thread),
               "Mismatch between thrd_t and internal Thread.");
 
 LLVM_LIBC_FUNCTION(int, thrd_detach, (thrd_t th)) {
@@ -23,4 +23,4 @@ LLVM_LIBC_FUNCTION(int, thrd_detach, (thrd_t th)) {
   return 0;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/thrd_detach.h b/libc/src/threads/thrd_detach.h
index 58d36e86380a..64f2094acd65 100644
--- a/libc/src/threads/thrd_detach.h
+++ b/libc/src/threads/thrd_detach.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int thrd_detach(thrd_t thread);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_THRD_DETACH_H
diff --git a/libc/src/threads/thrd_equal.cpp b/libc/src/threads/thrd_equal.cpp
index aac220ec9adb..b9717cf121b0 100644
--- a/libc/src/threads/thrd_equal.cpp
+++ b/libc/src/threads/thrd_equal.cpp
@@ -12,9 +12,9 @@
 
 #include <threads.h> // For thrd_* type definitions.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
-static_assert(sizeof(thrd_t) == sizeof(__llvm_libc::Thread),
+static_assert(sizeof(thrd_t) == sizeof(LIBC_NAMESPACE::Thread),
               "Mismatch between thrd_t and internal Thread.");
 
 LLVM_LIBC_FUNCTION(int, thrd_equal, (thrd_t lhs, thrd_t rhs)) {
@@ -23,4 +23,4 @@ LLVM_LIBC_FUNCTION(int, thrd_equal, (thrd_t lhs, thrd_t rhs)) {
   return *lhs_internal == *rhs_internal;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/thrd_equal.h b/libc/src/threads/thrd_equal.h
index 9e1bebc0afe5..5878ea458ba4 100644
--- a/libc/src/threads/thrd_equal.h
+++ b/libc/src/threads/thrd_equal.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int thrd_equal(thrd_t lhs, thrd_t rhs);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_THRD_EQUAL_H
diff --git a/libc/src/threads/thrd_exit.cpp b/libc/src/threads/thrd_exit.cpp
index 9935c23bba1e..67a7a419cf99 100644
--- a/libc/src/threads/thrd_exit.cpp
+++ b/libc/src/threads/thrd_exit.cpp
@@ -12,13 +12,13 @@
 
 #include <threads.h> // For thrd_* type definitions.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
-static_assert(sizeof(thrd_t) == sizeof(__llvm_libc::Thread),
+static_assert(sizeof(thrd_t) == sizeof(LIBC_NAMESPACE::Thread),
               "Mismatch between thrd_t and internal Thread.");
 
 LLVM_LIBC_FUNCTION(void, thrd_exit, (int retval)) {
   thread_exit(ThreadReturnValue(retval), ThreadStyle::STDC);
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/thrd_exit.h b/libc/src/threads/thrd_exit.h
index 4cc835118a85..19eb027d0357 100644
--- a/libc/src/threads/thrd_exit.h
+++ b/libc/src/threads/thrd_exit.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 void thrd_exit(int retval);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_THRD_EXIT_H
diff --git a/libc/src/threads/thrd_join.cpp b/libc/src/threads/thrd_join.cpp
index e4cf5522db92..cc8ba4b97a3a 100644
--- a/libc/src/threads/thrd_join.cpp
+++ b/libc/src/threads/thrd_join.cpp
@@ -12,9 +12,9 @@
 
 #include <threads.h> // For thrd_* type definitions.
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
-static_assert(sizeof(thrd_t) == sizeof(__llvm_libc::Thread),
+static_assert(sizeof(thrd_t) == sizeof(LIBC_NAMESPACE::Thread),
               "Mismatch between thrd_t and internal Thread.");
 
 LLVM_LIBC_FUNCTION(int, thrd_join, (thrd_t th, int *retval)) {
@@ -23,4 +23,4 @@ LLVM_LIBC_FUNCTION(int, thrd_join, (thrd_t th, int *retval)) {
   return result == 0 ? thrd_success : thrd_error;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/thrd_join.h b/libc/src/threads/thrd_join.h
index d86529c8cb97..21a398c6e835 100644
--- a/libc/src/threads/thrd_join.h
+++ b/libc/src/threads/thrd_join.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int thrd_join(thrd_t thread, int *retval);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_THRD_JOIN_H
diff --git a/libc/src/threads/tss_create.cpp b/libc/src/threads/tss_create.cpp
index f384565fbb9d..ddea44dce301 100644
--- a/libc/src/threads/tss_create.cpp
+++ b/libc/src/threads/tss_create.cpp
@@ -13,14 +13,14 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(int, tss_create, (tss_t * key, tss_dtor_t dtor)) {
-  auto k = __llvm_libc::new_tss_key(dtor);
+  auto k = LIBC_NAMESPACE::new_tss_key(dtor);
   if (!k)
     return thrd_error;
   *key = *k;
   return thrd_success;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/tss_create.h b/libc/src/threads/tss_create.h
index 967bdca10c4f..def903e29e06 100644
--- a/libc/src/threads/tss_create.h
+++ b/libc/src/threads/tss_create.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int tss_create(tss_t *key, tss_dtor_t dtor);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_TSS_CREATE_H
diff --git a/libc/src/threads/tss_delete.cpp b/libc/src/threads/tss_delete.cpp
index 6bdd4aa91867..a2a4e9aa349b 100644
--- a/libc/src/threads/tss_delete.cpp
+++ b/libc/src/threads/tss_delete.cpp
@@ -13,10 +13,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(void, tss_delete, (tss_t key)) {
-  __llvm_libc::tss_key_delete(key);
+  LIBC_NAMESPACE::tss_key_delete(key);
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/tss_delete.h b/libc/src/threads/tss_delete.h
index 1f55d3ba69f5..3efc0d745dd1 100644
--- a/libc/src/threads/tss_delete.h
+++ b/libc/src/threads/tss_delete.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 void tss_delete(tss_t key);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_TSS_DELETE_H
diff --git a/libc/src/threads/tss_get.cpp b/libc/src/threads/tss_get.cpp
index 4596a9337ffc..9b8c94fbeba2 100644
--- a/libc/src/threads/tss_get.cpp
+++ b/libc/src/threads/tss_get.cpp
@@ -13,8 +13,8 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(void *, tss_get, (tss_t key)) { return get_tss_value(key); }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/tss_get.h b/libc/src/threads/tss_get.h
index 4cedce988333..dfdb79cf122b 100644
--- a/libc/src/threads/tss_get.h
+++ b/libc/src/threads/tss_get.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 void *tss_get(tss_t);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_TSS_GET_H
diff --git a/libc/src/threads/tss_set.cpp b/libc/src/threads/tss_set.cpp
index 977168a2a98c..640896d14e1c 100644
--- a/libc/src/threads/tss_set.cpp
+++ b/libc/src/threads/tss_set.cpp
@@ -13,7 +13,7 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(int, tss_set, (tss_t key, void *data)) {
   if (set_tss_value(key, data))
@@ -22,4 +22,4 @@ LLVM_LIBC_FUNCTION(int, tss_set, (tss_t key, void *data)) {
     return thrd_error;
 }
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/threads/tss_set.h b/libc/src/threads/tss_set.h
index 49d69efa62ad..249607fdc700 100644
--- a/libc/src/threads/tss_set.h
+++ b/libc/src/threads/tss_set.h
@@ -11,10 +11,10 @@
 
 #include <threads.h>
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 
 int tss_set(tss_t, void *);
 
-} // namespace __llvm_libc
+} // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC_THREADS_TSS_SET_H