diff --git a/libc/src/__support/File/linux/file.cpp b/libc/src/__support/File/linux/file.cpp
index 761e352f74ead..4594dadf1ccdf 100644
--- a/libc/src/__support/File/linux/file.cpp
+++ b/libc/src/__support/File/linux/file.cpp
@@ -19,8 +19,8 @@
 #include "src/__support/macros/config.h"
 
 #include "hdr/fcntl_macros.h" // For mode_t and other flags to the open syscall
-#include <sys/stat.h>    // For S_IS*, S_IF*, and S_IR* flags.
-#include <sys/syscall.h> // For syscall numbers
+#include <sys/stat.h>         // For S_IS*, S_IF*, and S_IR* flags.
+#include <sys/syscall.h>      // For syscall numbers
 
 namespace LIBC_NAMESPACE_DECL {
 
@@ -128,10 +128,11 @@ ErrorOr<LinuxFile *> create_file_from_fd(int fd, const char *mode) {
     return Error(EINVAL);
   }
 
-  int fd_flags = internal::fcntl(fd, F_GETFL);
-  if (fd_flags == -1) {
+  auto result = internal::fcntl(fd, F_GETFL);
+  if (!result.has_value()) {
     return Error(EBADF);
   }
+  int fd_flags = result.value();
 
   using OpenMode = File::OpenMode;
   if (((fd_flags & O_ACCMODE) == O_RDONLY &&
@@ -145,8 +146,9 @@ ErrorOr<LinuxFile *> create_file_from_fd(int fd, const char *mode) {
   if ((modeflags & static_cast<ModeFlags>(OpenMode::APPEND)) &&
       !(fd_flags & O_APPEND)) {
     do_seek = true;
-    if (internal::fcntl(fd, F_SETFL,
-                        reinterpret_cast<void *>(fd_flags | O_APPEND)) == -1) {
+    if (!internal::fcntl(fd, F_SETFL,
+                         reinterpret_cast<void *>(fd_flags | O_APPEND))
+             .has_value()) {
       return Error(EBADF);
     }
   }
diff --git a/libc/src/__support/OSUtil/fcntl.h b/libc/src/__support/OSUtil/fcntl.h
index 46f7d28132396..3983d78f7f89c 100644
--- a/libc/src/__support/OSUtil/fcntl.h
+++ b/libc/src/__support/OSUtil/fcntl.h
@@ -8,12 +8,18 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FCNTL_H
 #define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FCNTL_H
 
+#include "hdr/types/mode_t.h"
+#include "src/__support/error_or.h"
 #include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
-int fcntl(int fd, int cmd, void *arg = nullptr);
+ErrorOr<int> fcntl(int fd, int cmd, void *arg = nullptr);
+
+ErrorOr<int> open(const char *path, int flags, mode_t mode_flags = 0);
+
+ErrorOr<int> close(int fd);
 
 } // namespace internal
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/OSUtil/linux/CMakeLists.txt b/libc/src/__support/OSUtil/linux/CMakeLists.txt
index b9704d42cd33b..4681d8c2bb73c 100644
--- a/libc/src/__support/OSUtil/linux/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/linux/CMakeLists.txt
@@ -16,7 +16,6 @@ add_object_library(
     .${LIBC_TARGET_ARCHITECTURE}.linux_${LIBC_TARGET_ARCHITECTURE}_util
     libc.src.__support.common
     libc.src.__support.CPP.string_view
-    libc.src.errno.errno
     libc.hdr.fcntl_macros
     libc.hdr.types.struct_flock
     libc.hdr.types.struct_flock64
diff --git a/libc/src/__support/OSUtil/linux/fcntl.cpp b/libc/src/__support/OSUtil/linux/fcntl.cpp
index 99e16ad58c918..bb76eee90efd2 100644
--- a/libc/src/__support/OSUtil/linux/fcntl.cpp
+++ b/libc/src/__support/OSUtil/linux/fcntl.cpp
@@ -8,23 +8,24 @@
 
 #include "src/__support/OSUtil/fcntl.h"
 
+#include "hdr/errno_macros.h"
 #include "hdr/fcntl_macros.h"
+#include "hdr/types/mode_t.h"
 #include "hdr/types/off_t.h"
 #include "hdr/types/struct_f_owner_ex.h"
 #include "hdr/types/struct_flock.h"
 #include "hdr/types/struct_flock64.h"
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
-#include "src/__support/libc_errno.h"
+#include "src/__support/error_or.h"
 #include "src/__support/macros/config.h"
 
-#include <stdarg.h>
 #include <sys/syscall.h> // For syscall numbers.
 
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
-int fcntl(int fd, int cmd, void *arg) {
+ErrorOr<int> fcntl(int fd, int cmd, void *arg) {
 #if SYS_fcntl
   constexpr auto FCNTL_SYSCALL_ID = SYS_fcntl;
 #elif defined(SYS_fcntl64)
@@ -33,8 +34,7 @@ int fcntl(int fd, int cmd, void *arg) {
 #error "fcntl and fcntl64 syscalls not available."
 #endif
 
-  int new_cmd = cmd;
-  switch (new_cmd) {
+  switch (cmd) {
   case F_OFD_SETLKW: {
     struct flock *flk = reinterpret_cast<struct flock *>(arg);
     // convert the struct to a flock64
@@ -45,8 +45,11 @@ int fcntl(int fd, int cmd, void *arg) {
     flk64.l_len = flk->l_len;
     flk64.l_pid = flk->l_pid;
     // create a syscall
-    return LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd, new_cmd,
-                                             &flk64);
+    int ret =
+        LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd, cmd, &flk64);
+    if (ret < 0)
+      return Error(-ret);
+    return ret;
   }
   case F_OFD_GETLK:
   case F_OFD_SETLK: {
@@ -59,60 +62,80 @@ int fcntl(int fd, int cmd, void *arg) {
     flk64.l_len = flk->l_len;
     flk64.l_pid = flk->l_pid;
     // create a syscall
-    int retVal = LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd,
-                                                   new_cmd, &flk64);
+    int ret =
+        LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd, cmd, &flk64);
     // On failure, return
-    if (retVal == -1)
-      return -1;
+    if (ret < 0)
+      return Error(-1);
     // Check for overflow, i.e. the offsets are not the same when cast
     // to off_t from off64_t.
     if (static_cast<off_t>(flk64.l_len) != flk64.l_len ||
-        static_cast<off_t>(flk64.l_start) != flk64.l_start) {
-      libc_errno = EOVERFLOW;
-      return -1;
-    }
+        static_cast<off_t>(flk64.l_start) != flk64.l_start)
+      return Error(EOVERFLOW);
+
     // Now copy back into flk, in case flk64 got modified
     flk->l_type = flk64.l_type;
     flk->l_whence = flk64.l_whence;
     flk->l_start = static_cast<decltype(flk->l_start)>(flk64.l_start);
     flk->l_len = static_cast<decltype(flk->l_len)>(flk64.l_len);
     flk->l_pid = flk64.l_pid;
-    return retVal;
+    return ret;
   }
   case F_GETOWN: {
     struct f_owner_ex fex;
     int ret = LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd,
                                                 F_GETOWN_EX, &fex);
-    if (ret >= 0)
-      return fex.type == F_OWNER_PGRP ? -fex.pid : fex.pid;
-    libc_errno = -ret;
-    return -1;
+    if (ret < 0)
+      return Error(-ret);
+    return fex.type == F_OWNER_PGRP ? -fex.pid : fex.pid;
   }
 #ifdef SYS_fcntl64
   case F_GETLK: {
     if constexpr (FCNTL_SYSCALL_ID == SYS_fcntl64)
-      new_cmd = F_GETLK64;
+      cmd = F_GETLK64;
     break;
   }
   case F_SETLK: {
     if constexpr (FCNTL_SYSCALL_ID == SYS_fcntl64)
-      new_cmd = F_SETLK64;
+      cmd = F_SETLK64;
     break;
   }
   case F_SETLKW: {
     if constexpr (FCNTL_SYSCALL_ID == SYS_fcntl64)
-      new_cmd = F_SETLKW64;
+      cmd = F_SETLKW64;
     break;
   }
 #endif
   }
-  int retVal = LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd, new_cmd,
-                                                 reinterpret_cast<void *>(arg));
-  if (retVal >= 0) {
-    return retVal;
-  }
-  libc_errno = -retVal;
-  return -1;
+
+  // default, but may use rewritten cmd from above.
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd, cmd,
+                                              reinterpret_cast<void *>(arg));
+  if (ret < 0)
+    return Error(-ret);
+  return ret;
+}
+
+ErrorOr<int> open(const char *path, int flags, mode_t mode_flags) {
+#ifdef SYS_open
+  int fd = LIBC_NAMESPACE::syscall_impl<int>(SYS_open, path, flags, mode_flags);
+#else
+  int fd = LIBC_NAMESPACE::syscall_impl<int>(SYS_openat, AT_FDCWD, path, flags,
+                                             mode_flags);
+#endif
+  if (fd < 0)
+    return Error(-fd);
+
+  return fd;
+}
+
+ErrorOr<int> close(int fd) {
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_close, fd);
+
+  if (ret < 0)
+    return Error(-ret);
+
+  return ret;
 }
 
 } // namespace internal
diff --git a/libc/src/fcntl/linux/CMakeLists.txt b/libc/src/fcntl/linux/CMakeLists.txt
index 580db16cd4132..c31eb3f438c10 100644
--- a/libc/src/fcntl/linux/CMakeLists.txt
+++ b/libc/src/fcntl/linux/CMakeLists.txt
@@ -19,6 +19,7 @@ add_entrypoint_object(
   DEPENDS
     libc.hdr.fcntl_macros
     libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
diff --git a/libc/src/fcntl/linux/fcntl.cpp b/libc/src/fcntl/linux/fcntl.cpp
index a0c8459ced342..fd9c48eb562f7 100644
--- a/libc/src/fcntl/linux/fcntl.cpp
+++ b/libc/src/fcntl/linux/fcntl.cpp
@@ -10,6 +10,7 @@
 
 #include "src/__support/OSUtil/fcntl.h"
 #include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
 
 #include <stdarg.h>
@@ -22,7 +23,14 @@ LLVM_LIBC_FUNCTION(int, fcntl, (int fd, int cmd, ...)) {
   va_start(varargs, cmd);
   arg = va_arg(varargs, void *);
   va_end(varargs);
-  return LIBC_NAMESPACE::internal::fcntl(fd, cmd, arg);
+
+  auto result = LIBC_NAMESPACE::internal::fcntl(fd, cmd, arg);
+
+  if (!result.has_value()) {
+    libc_errno = result.error();
+    return -1;
+  }
+  return result.value();
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/fcntl/linux/open.cpp b/libc/src/fcntl/linux/open.cpp
index a21a03788deaa..3a56d10554198 100644
--- a/libc/src/fcntl/linux/open.cpp
+++ b/libc/src/fcntl/linux/open.cpp
@@ -8,15 +8,13 @@
 
 #include "src/fcntl/open.h"
 
-#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "hdr/fcntl_macros.h"
+#include "hdr/types/mode_t.h"
+#include "src/__support/OSUtil/fcntl.h"
 #include "src/__support/common.h"
 #include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
-
-#include "hdr/fcntl_macros.h"
-#include "hdr/types/mode_t.h"
 #include <stdarg.h>
-#include <sys/syscall.h> // For syscall numbers.
 
 namespace LIBC_NAMESPACE_DECL {
 
@@ -31,17 +29,13 @@ LLVM_LIBC_FUNCTION(int, open, (const char *path, int flags, ...)) {
     va_end(varargs);
   }
 
-#ifdef SYS_open
-  int fd = LIBC_NAMESPACE::syscall_impl<int>(SYS_open, path, flags, mode_flags);
-#else
-  int fd = LIBC_NAMESPACE::syscall_impl<int>(SYS_openat, AT_FDCWD, path, flags,
-                                             mode_flags);
-#endif
-  if (fd > 0)
-    return fd;
+  auto result = internal::open(path, flags, mode_flags);
 
-  libc_errno = -fd;
-  return -1;
+  if (!result.has_value()) {
+    libc_errno = result.error();
+    return -1;
+  }
+  return result.value();
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/sys/auxv/linux/getauxval.cpp b/libc/src/sys/auxv/linux/getauxval.cpp
index f3ae7c5c4e07a..b50c5845bcc2b 100644
--- a/libc/src/sys/auxv/linux/getauxval.cpp
+++ b/libc/src/sys/auxv/linux/getauxval.cpp
@@ -8,6 +8,8 @@
 
 #include "src/sys/auxv/getauxval.h"
 #include "config/app.h"
+#include "hdr/fcntl_macros.h"
+#include "src/__support/OSUtil/fcntl.h"
 #include "src/__support/common.h"
 #include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
@@ -17,14 +19,18 @@
 #include "src/__support/threads/callonce.h"
 #include "src/__support/threads/linux/futex_word.h"
 
+// -----------------------------------------------------------------------------
+// TODO: This file should not include other public libc functions. Calling other
+// public libc functions is an antipattern within LLVM-libc. This needs to be
+// cleaned up. DO NOT COPY THIS.
+// -----------------------------------------------------------------------------
+
 // for mallocing the global auxv
 #include "src/sys/mman/mmap.h"
 #include "src/sys/mman/munmap.h"
 
 // for reading /proc/self/auxv
-#include "src/fcntl/open.h"
 #include "src/sys/prctl/prctl.h"
-#include "src/unistd/close.h"
 #include "src/unistd/read.h"
 
 // getauxval will work either with or without __cxa_atexit support.
@@ -60,17 +66,18 @@ class AuxvMMapGuard {
   constexpr static size_t AUXV_MMAP_SIZE = sizeof(AuxEntry) * MAX_AUXV_ENTRIES;
 
   AuxvMMapGuard()
-      : ptr(mmap(nullptr, AUXV_MMAP_SIZE, PROT_READ | PROT_WRITE,
-                 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)) {}
+      : ptr(LIBC_NAMESPACE::mmap(nullptr, AUXV_MMAP_SIZE,
+                                 PROT_READ | PROT_WRITE,
+                                 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)) {}
   ~AuxvMMapGuard() {
     if (ptr != MAP_FAILED)
-      munmap(ptr, AUXV_MMAP_SIZE);
+      LIBC_NAMESPACE::munmap(ptr, AUXV_MMAP_SIZE);
   }
   void submit_to_global() {
     // atexit may fail, we do not set it to global in that case.
     int ret = __cxa_atexit(
         [](void *) {
-          munmap(auxv, AUXV_MMAP_SIZE);
+          LIBC_NAMESPACE::munmap(auxv, AUXV_MMAP_SIZE);
           auxv = nullptr;
         },
         nullptr, nullptr);
@@ -90,10 +97,16 @@ class AuxvMMapGuard {
 
 class AuxvFdGuard {
 public:
-  AuxvFdGuard() : fd(open("/proc/self/auxv", O_RDONLY | O_CLOEXEC)) {}
+  AuxvFdGuard() {
+    auto result = internal::open("/proc/self/auxv", O_RDONLY | O_CLOEXEC);
+    if (!result.has_value())
+      fd = -1;
+
+    fd = result.value();
+  }
   ~AuxvFdGuard() {
     if (fd != -1)
-      close(fd);
+      internal::close(fd);
   }
   bool valid() const { return fd != -1; }
   int get() const { return fd; }
@@ -135,7 +148,8 @@ static void initialize_auxv_once(void) {
   bool error_detected = false;
   // Read until we use up all the available space or we finish reading the file.
   while (available_size != 0) {
-    ssize_t bytes_read = read(fd_guard.get(), buf, available_size);
+    ssize_t bytes_read =
+        LIBC_NAMESPACE::read(fd_guard.get(), buf, available_size);
     if (bytes_read <= 0) {
       if (libc_errno == EINTR)
         continue;
@@ -158,7 +172,7 @@ static AuxEntry read_entry(int fd) {
   size_t size = sizeof(AuxEntry);
   char *ptr = reinterpret_cast<char *>(&buf);
   while (size > 0) {
-    ssize_t ret = read(fd, ptr, size);
+    ssize_t ret = LIBC_NAMESPACE::read(fd, ptr, size);
     if (ret < 0) {
       if (libc_errno == EINTR)
         continue;
@@ -195,7 +209,8 @@ LLVM_LIBC_FUNCTION(unsigned long, getauxval, (unsigned long id)) {
     return search_auxv(app.auxv_ptr, id);
 
   static FutexWordType once_flag;
-  callonce(reinterpret_cast<CallOnceFlag *>(&once_flag), initialize_auxv_once);
+  LIBC_NAMESPACE::callonce(reinterpret_cast<CallOnceFlag *>(&once_flag),
+                           initialize_auxv_once);
   if (auxv != nullptr)
     return search_auxv(auxv, id);
 
diff --git a/libc/src/sys/mman/linux/shm_common.h b/libc/src/sys/mman/linux/shm_common.h
index 69911012ff7e9..29d1401821e49 100644
--- a/libc/src/sys/mman/linux/shm_common.h
+++ b/libc/src/sys/mman/linux/shm_common.h
@@ -13,6 +13,11 @@
 #include "src/__support/macros/config.h"
 #include "src/string/memory_utils/inline_memcpy.h"
 
+// TODO: clean this up.
+//  1. Change from optional to ErrorOr, and return the errno instead of setting
+//    it here.
+//  2. Replace inline memcpy with __builtin_memcpy
+
 // TODO: Get PATH_MAX via https://github.com/llvm/llvm-project/issues/85121
 #include <linux/limits.h>
 
diff --git a/libc/src/sys/mman/linux/shm_open.cpp b/libc/src/sys/mman/linux/shm_open.cpp
index 11de482272d00..3099062eace98 100644
--- a/libc/src/sys/mman/linux/shm_open.cpp
+++ b/libc/src/sys/mman/linux/shm_open.cpp
@@ -7,9 +7,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/sys/mman/shm_open.h"
+#include "hdr/fcntl_macros.h"
 #include "hdr/types/mode_t.h"
+#include "src/__support/OSUtil/fcntl.h"
 #include "src/__support/macros/config.h"
-#include "src/fcntl/open.h"
 #include "src/sys/mman/linux/shm_common.h"
 
 namespace LIBC_NAMESPACE_DECL {
@@ -17,9 +18,16 @@ namespace LIBC_NAMESPACE_DECL {
 static constexpr int DEFAULT_OFLAGS = O_NOFOLLOW | O_CLOEXEC | O_NONBLOCK;
 
 LLVM_LIBC_FUNCTION(int, shm_open, (const char *name, int oflags, mode_t mode)) {
-  using namespace shm_common;
-  if (cpp::optional<SHMPath> buffer = translate_name(name))
-    return open(buffer->data(), oflags | DEFAULT_OFLAGS, mode);
+  if (cpp::optional<shm_common::SHMPath> buffer =
+          shm_common::translate_name(name)) {
+    auto result = internal::open(buffer->data(), oflags | DEFAULT_OFLAGS, mode);
+
+    if (!result.has_value()) {
+      libc_errno = result.error();
+      return -1;
+    }
+    return result.value();
+  }
   return -1;
 }
 
diff --git a/libc/src/sys/mman/linux/shm_unlink.cpp b/libc/src/sys/mman/linux/shm_unlink.cpp
index 6a76301512201..4c61c7cd16bad 100644
--- a/libc/src/sys/mman/linux/shm_unlink.cpp
+++ b/libc/src/sys/mman/linux/shm_unlink.cpp
@@ -13,10 +13,13 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
+// TODO: stop calling the public unlink function. It should be calling an
+// internal shared utility.
+
 LLVM_LIBC_FUNCTION(int, shm_unlink, (const char *name)) {
-  using namespace shm_common;
-  if (cpp::optional<SHMPath> buffer = translate_name(name))
-    return unlink(buffer->data());
+  if (cpp::optional<shm_common::SHMPath> buffer =
+          shm_common::translate_name(name))
+    return LIBC_NAMESPACE::unlink(buffer->data());
   return -1;
 }
 
diff --git a/libc/src/unistd/linux/close.cpp b/libc/src/unistd/linux/close.cpp
index b5842f2b64d20..6ef3a3c6d63f0 100644
--- a/libc/src/unistd/linux/close.cpp
+++ b/libc/src/unistd/linux/close.cpp
@@ -8,9 +8,8 @@
 
 #include "src/unistd/close.h"
 
-#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/OSUtil/fcntl.h"
 #include "src/__support/common.h"
-
 #include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
 #include <sys/syscall.h> // For syscall numbers.
@@ -18,12 +17,13 @@
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, close, (int fd)) {
-  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_close, fd);
-  if (ret < 0) {
-    libc_errno = -ret;
+  auto result = internal::close(fd);
+
+  if (!result.has_value()) {
+    libc_errno = result.error();
     return -1;
   }
-  return ret;
+  return result.value();
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 84a6b7d230442..7901de161b7ac 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -344,6 +344,21 @@ libc_support_library(
     hdrs = ["hdr/types/struct_epoll_event.h"],
 )
 
+libc_support_library(
+    name = "types_struct_f_owner_ex",
+    hdrs = ["hdr/types/struct_f_owner_ex.h"],
+)
+
+libc_support_library(
+    name = "types_struct_flock",
+    hdrs = ["hdr/types/struct_flock.h"],
+)
+
+libc_support_library(
+    name = "types_struct_flock64",
+    hdrs = ["hdr/types/struct_flock64.h"],
+)
+
 libc_support_library(
     name = "types_struct_timespec",
     hdrs = ["hdr/types/struct_timespec.h"],
@@ -1380,6 +1395,28 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_osutil_fcntl",
+    srcs = ["src/__support/OSUtil/linux/fcntl.cpp"],
+    hdrs = ["src/__support/OSUtil/fcntl.h"],
+    target_compatible_with = select({
+        "@platforms//os:linux": [],
+        "//conditions:default": ["@platforms//:incompatible"],
+    }),
+    deps = [
+        ":__support_common",
+        ":__support_error_or",
+        ":__support_osutil_syscall",
+        ":hdr_errno_macros",
+        ":hdr_fcntl_macros",
+        ":types_mode_t",
+        ":types_off_t",
+        ":types_struct_f_owner_ex",
+        ":types_struct_flock",
+        ":types_struct_flock64",
+    ],
+)
+
 libc_support_library(
     name = "__support_osutil_exit",
     srcs = ["src/__support/OSUtil/linux/exit.cpp"],
@@ -1601,8 +1638,8 @@ libc_support_library(
 libc_header_library(
     name = "libcxx_shared_headers",
     hdrs = [
-        "shared/libc_common.h",
         "shared/fp_bits.h",
+        "shared/libc_common.h",
         "shared/str_to_float.h",
         "shared/str_to_integer.h",
     ],
@@ -4475,13 +4512,28 @@ libc_function(
     }),
     deps = [
         ":__support_common",
-        ":__support_osutil_syscall",
+        ":__support_osutil_fcntl",
         ":errno",
         ":hdr_fcntl_macros",
         ":types_mode_t",
     ],
 )
 
+libc_function(
+    name = "fcntl",
+    srcs = ["src/fcntl/linux/fcntl.cpp"],
+    hdrs = ["src/fcntl/fcntl.h"],
+    target_compatible_with = select({
+        "@platforms//os:linux": [],
+        "//conditions:default": ["@platforms//:incompatible"],
+    }),
+    deps = [
+        ":__support_common",
+        ":__support_osutil_fcntl",
+        ":errno",
+    ],
+)
+
 libc_function(
     name = "openat",
     srcs = ["src/fcntl/linux/openat.cpp"],
@@ -4542,7 +4594,7 @@ libc_function(
     hdrs = ["src/unistd/close.h"],
     deps = [
         ":__support_common",
-        ":__support_osutil_syscall",
+        ":__support_osutil_fcntl",
         ":errno",
     ],
 )