diff --git a/libc/config/linux/app.h b/libc/config/linux/app.h
index f3d11da9fc14c..11ac6ee51e5a0 100644
--- a/libc/config/linux/app.h
+++ b/libc/config/linux/app.h
@@ -35,17 +35,6 @@ struct TLSImage {
   uintptr_t align;
 };
 
-// Linux manpage on `proc(5)` says that the aux vector is an array of
-// unsigned long pairs.
-// (see: https://man7.org/linux/man-pages/man5/proc.5.html)
-using AuxEntryType = unsigned long;
-// Using the naming convention from `proc(5)`.
-// TODO: Would be nice to use the aux entry structure from elf.h when available.
-struct AuxEntry {
-  AuxEntryType id;
-  AuxEntryType value;
-};
-
 struct Args {
   uintptr_t argc;
 
@@ -70,9 +59,6 @@ struct AppProperties {
 
   // Environment data.
   uintptr_t *env_ptr;
-
-  // Auxiliary vector data.
-  AuxEntry *auxv_ptr;
 };
 
 [[gnu::weak]] extern AppProperties app;
diff --git a/libc/src/__support/OSUtil/linux/CMakeLists.txt b/libc/src/__support/OSUtil/linux/CMakeLists.txt
index f303e54ce7b3b..f6377ca9ff5a2 100644
--- a/libc/src/__support/OSUtil/linux/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/linux/CMakeLists.txt
@@ -24,6 +24,18 @@ add_object_library(
     libc.include.sys_syscall
 )
 
+add_header_library(
+  auxv
+  HDRS
+    auxv.h
+  DEPENDS
+    libc.hdr.fcntl_macros
+    libc.src.__support.OSUtil.osutil
+    libc.src.__support.common
+    libc.src.__support.CPP.optional
+    libc.src.__support.threads.callonce
+)
+
 add_header_library(
   getrandom
   HDRS
diff --git a/libc/src/__support/OSUtil/linux/auxv.h b/libc/src/__support/OSUtil/linux/auxv.h
new file mode 100644
index 0000000000000..17108e2e54794
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/auxv.h
@@ -0,0 +1,151 @@
+//===------------- Linux AUXV Header --------------------------*- 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___SUPPORT_OSUTIL_LINUX_AUXV_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_AUXV_H
+
+#include "hdr/fcntl_macros.h" // For open flags
+#include "src/__support/OSUtil/syscall.h"
+#include "src/__support/common.h"
+#include "src/__support/threads/callonce.h"
+
+#include <linux/auxvec.h> // For AT_ macros
+#include <linux/mman.h>   // For mmap flags
+#include <linux/prctl.h>  // For prctl
+#include <sys/syscall.h>  // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace auxv {
+struct Entry {
+  unsigned long type; // Entry type
+  unsigned long val;  // Integer value
+};
+
+class Vector {
+  LIBC_INLINE_VAR static constexpr Entry END = {AT_NULL, AT_NULL};
+  LIBC_INLINE_VAR static const Entry *entries = &END;
+  LIBC_INLINE_VAR static CallOnceFlag init_flag = callonce_impl::NOT_CALLED;
+  LIBC_INLINE_VAR constexpr static size_t FALLBACK_AUXV_ENTRIES = 64;
+
+  LIBC_INLINE static void fallback_initialize_unsync();
+  LIBC_INLINE static const Entry *get_entries() {
+    if (LIBC_LIKELY(entries != &END))
+      return entries;
+    callonce(&init_flag, fallback_initialize_unsync);
+    return entries;
+  }
+
+public:
+  class Iterator {
+    const Entry *current;
+
+  public:
+    LIBC_INLINE explicit Iterator(const Entry *entry) : current(entry) {}
+    LIBC_INLINE Iterator &operator++() {
+      ++current;
+      return *this;
+    }
+    LIBC_INLINE const Entry &operator*() const { return *current; }
+    LIBC_INLINE bool operator!=(const Iterator &other) const {
+      return current->type != other.current->type;
+    }
+    LIBC_INLINE bool operator==(const Iterator &other) const {
+      return current->type == other.current->type;
+    }
+  };
+  using iterator = Iterator;
+  LIBC_INLINE static Iterator begin() { return Iterator(get_entries()); }
+  LIBC_INLINE static Iterator end() { return Iterator(&END); }
+  LIBC_INLINE static void initialize_unsafe(const Entry *auxv);
+};
+
+// Initializes the auxv entries.
+// This function is intended to be called once inside crt0.
+LIBC_INLINE void Vector::initialize_unsafe(const Entry *auxv) {
+  init_flag = callonce_impl::FINISH;
+  entries = auxv;
+}
+
+// When CRT0 does not setup the global array, this function is called.
+// As its name suggests, this function is not thread-safe and should be
+// backed by a callonce guard.
+// This initialize routine will do a mmap to allocate a memory region.
+// Since auxv tends to live throughout the program lifetime, we do not
+// munmap it.
+[[gnu::cold]]
+LIBC_INLINE void Vector::fallback_initialize_unsync() {
+  constexpr size_t AUXV_MMAP_SIZE = FALLBACK_AUXV_ENTRIES * sizeof(Entry);
+  long mmap_ret = syscall_impl<long>(SYS_mmap, nullptr, AUXV_MMAP_SIZE,
+                                     PROT_READ | PROT_WRITE,
+                                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  // We do not proceed if mmap fails.
+  if (mmap_ret <= 0)
+    return;
+
+  // Initialize the auxv array with AT_NULL entries.
+  Entry *vector = reinterpret_cast<Entry *>(mmap_ret);
+  for (size_t i = 0; i < FALLBACK_AUXV_ENTRIES; ++i) {
+    vector[i].type = AT_NULL;
+    vector[i].val = AT_NULL;
+  }
+  size_t avaiable_size = AUXV_MMAP_SIZE - sizeof(Entry);
+
+  // Attempt 1: use PRCTL to get the auxv.
+  // We guarantee that the vector is always padded with AT_NULL entries.
+  long prctl_ret = syscall_impl<long>(SYS_prctl, PR_GET_AUXV,
+                                      reinterpret_cast<unsigned long>(vector),
+                                      avaiable_size, 0, 0);
+  if (prctl_ret >= 0) {
+    entries = vector;
+    return;
+  }
+
+  // Attempt 2: read /proc/self/auxv.
+#ifdef SYS_openat
+  int fd = syscall_impl<int>(SYS_openat, AT_FDCWD, "/proc/self/auxv",
+                             O_RDONLY | O_CLOEXEC);
+#else
+  int fd = syscall_impl<int>(SYS_open, "/proc/self/auxv", O_RDONLY | O_CLOEXEC);
+#endif
+  if (fd < 0) {
+    syscall_impl<long>(SYS_munmap, vector, AUXV_MMAP_SIZE);
+    return;
+  }
+  uint8_t *cursor = reinterpret_cast<uint8_t *>(vector);
+  bool has_error = false;
+  while (avaiable_size != 0) {
+    long bytes_read = syscall_impl<long>(SYS_read, fd, cursor, avaiable_size);
+    if (bytes_read <= 0) {
+      if (bytes_read == -EINTR)
+        continue;
+      has_error = bytes_read < 0;
+      break;
+    }
+    avaiable_size -= bytes_read;
+    cursor += bytes_read;
+  }
+  syscall_impl<long>(SYS_close, fd);
+  if (has_error) {
+    syscall_impl<long>(SYS_munmap, vector, AUXV_MMAP_SIZE);
+    return;
+  }
+  entries = vector;
+}
+
+LIBC_INLINE cpp::optional<unsigned long> get(unsigned long type) {
+  Vector auxvec;
+  for (const auto &entry : auxvec)
+    if (entry.type == type)
+      return entry.val;
+  return cpp::nullopt;
+}
+} // namespace auxv
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_AUXV_H
diff --git a/libc/src/__support/threads/callonce.h b/libc/src/__support/threads/callonce.h
index 5392722045c94..0ccbcf96b995a 100644
--- a/libc/src/__support/threads/callonce.h
+++ b/libc/src/__support/threads/callonce.h
@@ -23,14 +23,8 @@
 #endif
 
 namespace LIBC_NAMESPACE_DECL {
-
-// Common definitions
-using CallOnceCallback = void(void);
-namespace callonce_impl {
-int callonce_slowpath(CallOnceFlag *flag, CallOnceCallback *callback);
-} // namespace callonce_impl
-
-LIBC_INLINE int callonce(CallOnceFlag *flag, CallOnceCallback *callback) {
+template <class CallOnceCallback>
+LIBC_INLINE int callonce(CallOnceFlag *flag, CallOnceCallback callback) {
   if (LIBC_LIKELY(callonce_impl::callonce_fastpath(flag)))
     return 0;
 
diff --git a/libc/src/__support/threads/linux/CMakeLists.txt b/libc/src/__support/threads/linux/CMakeLists.txt
index 14aaad214f43a..39d2c6fef0fed 100644
--- a/libc/src/__support/threads/linux/CMakeLists.txt
+++ b/libc/src/__support/threads/linux/CMakeLists.txt
@@ -97,10 +97,8 @@ add_object_library(
                             # value other than 0 is dangerous. We know.
 )
 
-add_object_library(
+add_header_library(
   callonce
-  SRCS
-    callonce.cpp
   HDRS
     ../callonce.h
     callonce.h
diff --git a/libc/src/__support/threads/linux/callonce.cpp b/libc/src/__support/threads/linux/callonce.cpp
deleted file mode 100644
index c6e5f2aba69fc..0000000000000
--- a/libc/src/__support/threads/linux/callonce.cpp
+++ /dev/null
@@ -1,40 +0,0 @@
-//===-- Linux implementation of the callonce 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 "src/__support/threads/callonce.h"
-#include "src/__support/macros/config.h"
-#include "src/__support/threads/linux/callonce.h"
-#include "src/__support/threads/linux/futex_utils.h"
-
-namespace LIBC_NAMESPACE_DECL {
-namespace callonce_impl {
-int callonce_slowpath(CallOnceFlag *flag, CallOnceCallback *func) {
-  auto *futex_word = reinterpret_cast<Futex *>(flag);
-
-  FutexWordType not_called = NOT_CALLED;
-
-  // The call_once call can return only after the called function |func|
-  // returns. So, we use futexes to synchronize calls with the same flag value.
-  if (futex_word->compare_exchange_strong(not_called, START)) {
-    func();
-    auto status = futex_word->exchange(FINISH);
-    if (status == WAITING)
-      futex_word->notify_all();
-    return 0;
-  }
-
-  FutexWordType status = START;
-  if (futex_word->compare_exchange_strong(status, WAITING) ||
-      status == WAITING) {
-    futex_word->wait(WAITING);
-  }
-
-  return 0;
-}
-} // namespace callonce_impl
-} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/threads/linux/callonce.h b/libc/src/__support/threads/linux/callonce.h
index b3ea3a5b1c679..70872b6d90156 100644
--- a/libc/src/__support/threads/linux/callonce.h
+++ b/libc/src/__support/threads/linux/callonce.h
@@ -26,6 +26,31 @@ static constexpr FutexWordType FINISH = 0x33;
 LIBC_INLINE bool callonce_fastpath(CallOnceFlag *flag) {
   return flag->load(cpp::MemoryOrder::RELAXED) == FINISH;
 }
+
+template <class CallOnceCallback>
+[[gnu::noinline, gnu::cold]] int callonce_slowpath(CallOnceFlag *flag,
+                                                   CallOnceCallback callback) {
+
+  auto *futex_word = reinterpret_cast<Futex *>(flag);
+
+  FutexWordType not_called = NOT_CALLED;
+
+  // The call_once call can return only after the called function |func|
+  // returns. So, we use futexes to synchronize calls with the same flag value.
+  if (futex_word->compare_exchange_strong(not_called, START)) {
+    callback();
+    auto status = futex_word->exchange(FINISH);
+    if (status == WAITING)
+      futex_word->notify_all();
+    return 0;
+  }
+
+  FutexWordType status = START;
+  if (futex_word->compare_exchange_strong(status, WAITING) || status == WAITING)
+    futex_word->wait(WAITING);
+
+  return 0;
+}
 } // namespace callonce_impl
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/pthread/pthread_once.cpp b/libc/src/pthread/pthread_once.cpp
index d78644a8dab26..109f70c24f1cf 100644
--- a/libc/src/pthread/pthread_once.cpp
+++ b/libc/src/pthread/pthread_once.cpp
@@ -17,8 +17,7 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, pthread_once,
                    (pthread_once_t * flag, __pthread_once_func_t func)) {
-  return callonce(reinterpret_cast<CallOnceFlag *>(flag),
-                  reinterpret_cast<CallOnceCallback *>(func));
+  return callonce(reinterpret_cast<CallOnceFlag *>(flag), func);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/sys/auxv/linux/CMakeLists.txt b/libc/src/sys/auxv/linux/CMakeLists.txt
index 4884184cc6053..39cfb7ba3f7ee 100644
--- a/libc/src/sys/auxv/linux/CMakeLists.txt
+++ b/libc/src/sys/auxv/linux/CMakeLists.txt
@@ -5,15 +5,6 @@ add_entrypoint_object(
   HDRS
     ../getauxval.h
   DEPENDS
-    libc.src.sys.prctl.prctl
-    libc.src.sys.mman.mmap
-    libc.src.sys.mman.munmap
-    libc.src.__support.threads.callonce
-    libc.src.__support.common
-    libc.src.errno.errno
-    libc.config.app_h
-    libc.src.fcntl.open
-    libc.src.unistd.read
-    libc.src.unistd.close
-    libc.include.sys_auxv
+    libc.src.__support.OSUtil.linux.auxv
+    libc.src.__support.libc_errno
 )
diff --git a/libc/src/sys/auxv/linux/getauxval.cpp b/libc/src/sys/auxv/linux/getauxval.cpp
index b50c5845bcc2b..52d5a988a9494 100644
--- a/libc/src/sys/auxv/linux/getauxval.cpp
+++ b/libc/src/sys/auxv/linux/getauxval.cpp
@@ -7,227 +7,14 @@
 //===----------------------------------------------------------------------===//
 
 #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/OSUtil/linux/auxv.h"
 #include "src/__support/libc_errno.h"
-#include "src/__support/macros/config.h"
-#include <linux/auxvec.h>
-
-// for guarded initialization
-#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/sys/prctl/prctl.h"
-#include "src/unistd/read.h"
-
-// getauxval will work either with or without __cxa_atexit support.
-// In order to detect if __cxa_atexit is supported, we define a weak symbol.
-// We prefer __cxa_atexit as it is always defined as a C symbol whileas atexit
-// may not be created via objcopy yet. Also, for glibc, atexit is provided via
-// libc_nonshared.a rather than libc.so. So, it is may not be made ready for
-// overlay builds.
-extern "C" [[gnu::weak]] int __cxa_atexit(void (*callback)(void *),
-                                          void *payload, void *);
 
 namespace LIBC_NAMESPACE_DECL {
-
-constexpr static size_t MAX_AUXV_ENTRIES = 64;
-
-// Helper to recover or set errno
-class AuxvErrnoGuard {
-public:
-  AuxvErrnoGuard() : saved(libc_errno), failure(false) {}
-  ~AuxvErrnoGuard() { libc_errno = failure ? ENOENT : saved; }
-  void mark_failure() { failure = true; }
-
-private:
-  int saved;
-  bool failure;
-};
-
-// Helper to manage the memory
-static AuxEntry *auxv = nullptr;
-
-class AuxvMMapGuard {
-public:
-  constexpr static size_t AUXV_MMAP_SIZE = sizeof(AuxEntry) * MAX_AUXV_ENTRIES;
-
-  AuxvMMapGuard()
-      : ptr(LIBC_NAMESPACE::mmap(nullptr, AUXV_MMAP_SIZE,
-                                 PROT_READ | PROT_WRITE,
-                                 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)) {}
-  ~AuxvMMapGuard() {
-    if (ptr != MAP_FAILED)
-      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 *) {
-          LIBC_NAMESPACE::munmap(auxv, AUXV_MMAP_SIZE);
-          auxv = nullptr;
-        },
-        nullptr, nullptr);
-
-    if (ret != 0)
-      return;
-
-    auxv = reinterpret_cast<AuxEntry *>(ptr);
-    ptr = MAP_FAILED;
-  }
-  bool allocated() const { return ptr != MAP_FAILED; }
-  void *get() const { return ptr; }
-
-private:
-  void *ptr;
-};
-
-class AuxvFdGuard {
-public:
-  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)
-      internal::close(fd);
-  }
-  bool valid() const { return fd != -1; }
-  int get() const { return fd; }
-
-private:
-  int fd;
-};
-
-static void initialize_auxv_once(void) {
-  // If we cannot get atexit, we cannot register the cleanup function.
-  if (&__cxa_atexit == nullptr)
-    return;
-
-  AuxvMMapGuard mmap_guard;
-  if (!mmap_guard.allocated())
-    return;
-  auto *ptr = reinterpret_cast<AuxEntry *>(mmap_guard.get());
-
-  // We get one less than the max size to make sure the search always
-  // terminates. MMAP private pages are zeroed out already.
-  size_t available_size = AuxvMMapGuard::AUXV_MMAP_SIZE - sizeof(AuxEntryType);
-  // PR_GET_AUXV is only available on Linux kernel 6.1 and above. If this is not
-  // defined, we direcly fall back to reading /proc/self/auxv. In case the libc
-  // is compiled and run on separate kernels, we also check the return value of
-  // prctl.
-#ifdef PR_GET_AUXV
-  int ret = prctl(PR_GET_AUXV, reinterpret_cast<unsigned long>(ptr),
-                  available_size, 0, 0);
-  if (ret >= 0) {
-    mmap_guard.submit_to_global();
-    return;
-  }
-#endif
-  AuxvFdGuard fd_guard;
-  if (!fd_guard.valid())
-    return;
-  auto *buf = reinterpret_cast<char *>(ptr);
-  libc_errno = 0;
-  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 =
-        LIBC_NAMESPACE::read(fd_guard.get(), buf, available_size);
-    if (bytes_read <= 0) {
-      if (libc_errno == EINTR)
-        continue;
-      // Now, we either have an non-recoverable error or we have reached the end
-      // of the file. Mark `error_detected` accordingly.
-      if (bytes_read == -1)
-        error_detected = true;
-      break;
-    }
-    buf += bytes_read;
-    available_size -= bytes_read;
-  }
-  // If we get out of the loop without an error, the auxv is ready.
-  if (!error_detected)
-    mmap_guard.submit_to_global();
-}
-
-static AuxEntry read_entry(int fd) {
-  AuxEntry buf;
-  size_t size = sizeof(AuxEntry);
-  char *ptr = reinterpret_cast<char *>(&buf);
-  while (size > 0) {
-    ssize_t ret = LIBC_NAMESPACE::read(fd, ptr, size);
-    if (ret < 0) {
-      if (libc_errno == EINTR)
-        continue;
-      // Error detected, return AT_NULL
-      buf.id = AT_NULL;
-      buf.value = AT_NULL;
-      break;
-    }
-    ptr += ret;
-    size -= ret;
-  }
-  return buf;
-}
-
 LLVM_LIBC_FUNCTION(unsigned long, getauxval, (unsigned long id)) {
-  // Fast path when libc is loaded by its own initialization code. In this case,
-  // app.auxv_ptr is already set to the auxv passed on the initial stack of the
-  // process.
-  AuxvErrnoGuard errno_guard;
-
-  auto search_auxv = [&errno_guard](AuxEntry *auxv,
-                                    unsigned long id) -> AuxEntryType {
-    for (auto *ptr = auxv; ptr->id != AT_NULL; ptr++)
-      if (ptr->id == id)
-        return ptr->value;
-
-    errno_guard.mark_failure();
-    return AT_NULL;
-  };
-
-  // App is a weak symbol that is only defined if libc is linked to its own
-  // initialization routine. We need to check if it is null.
-  if (&app != nullptr)
-    return search_auxv(app.auxv_ptr, id);
-
-  static FutexWordType once_flag;
-  LIBC_NAMESPACE::callonce(reinterpret_cast<CallOnceFlag *>(&once_flag),
-                           initialize_auxv_once);
-  if (auxv != nullptr)
-    return search_auxv(auxv, id);
-
-  // Fallback to use read without mmap
-  AuxvFdGuard fd_guard;
-  if (fd_guard.valid()) {
-    while (true) {
-      AuxEntry buf = read_entry(fd_guard.get());
-      if (buf.id == AT_NULL)
-        break;
-      if (buf.id == id)
-        return buf.value;
-    }
-  }
-
-  // cannot find the entry after all methods, mark failure and return 0
-  errno_guard.mark_failure();
-  return AT_NULL;
+  if (cpp::optional<unsigned long> val = auxv::get(id))
+    return *val;
+  libc_errno = ENOENT;
+  return 0;
 }
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/threads/call_once.cpp b/libc/src/threads/call_once.cpp
index 8466cd622afeb..b60a20d1cdd15 100644
--- a/libc/src/threads/call_once.cpp
+++ b/libc/src/threads/call_once.cpp
@@ -17,8 +17,7 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(void, call_once,
                    (once_flag * flag, __call_once_func_t func)) {
-  callonce(reinterpret_cast<CallOnceFlag *>(flag),
-           reinterpret_cast<CallOnceCallback *>(func));
+  callonce(reinterpret_cast<CallOnceFlag *>(flag), func);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/startup/linux/CMakeLists.txt b/libc/startup/linux/CMakeLists.txt
index 7af1819c57c17..df2c4b9ec508c 100644
--- a/libc/startup/linux/CMakeLists.txt
+++ b/libc/startup/linux/CMakeLists.txt
@@ -105,6 +105,7 @@ add_object_library(
     libc.src.stdlib.exit
     libc.src.stdlib.atexit
     libc.src.unistd.environ
+    libc.src.__support.OSUtil.linux.auxv
   COMPILE_OPTIONS
     -ffreestanding       # To avoid compiler warnings about calling the main function.
     -fno-builtin         # avoid emit unexpected calls
diff --git a/libc/startup/linux/do_start.cpp b/libc/startup/linux/do_start.cpp
index 94c4ec7092861..a67bf188b1ae3 100644
--- a/libc/startup/linux/do_start.cpp
+++ b/libc/startup/linux/do_start.cpp
@@ -9,6 +9,7 @@
 #include "config/linux/app.h"
 #include "hdr/stdint_proxy.h"
 #include "include/llvm-libc-macros/link-macros.h"
+#include "src/__support/OSUtil/linux/auxv.h"
 #include "src/__support/OSUtil/syscall.h"
 #include "src/__support/macros/config.h"
 #include "src/__support/threads/thread.h"
@@ -88,17 +89,19 @@ void teardown_main_tls() { cleanup_tls(tls.addr, tls.size); }
   // denoted by an AT_NULL entry.
   ElfW(Phdr) *program_hdr_table = nullptr;
   uintptr_t program_hdr_count = 0;
-  app.auxv_ptr = reinterpret_cast<AuxEntry *>(env_end_marker + 1);
-  for (auto *aux_entry = app.auxv_ptr; aux_entry->id != AT_NULL; ++aux_entry) {
-    switch (aux_entry->id) {
+  auxv::Vector::initialize_unsafe(
+      reinterpret_cast<const auxv::Entry *>(env_end_marker + 1));
+  auxv::Vector auxvec;
+  for (const auto &aux_entry : auxvec) {
+    switch (aux_entry.type) {
     case AT_PHDR:
-      program_hdr_table = reinterpret_cast<ElfW(Phdr) *>(aux_entry->value);
+      program_hdr_table = reinterpret_cast<ElfW(Phdr) *>(aux_entry.val);
       break;
     case AT_PHNUM:
-      program_hdr_count = aux_entry->value;
+      program_hdr_count = aux_entry.val;
       break;
     case AT_PAGESZ:
-      app.page_size = aux_entry->value;
+      app.page_size = aux_entry.val;
       break;
     default:
       break; // TODO: Read other useful entries from the aux vector.