diff --git a/crypto/cpu_arm_linux.c b/crypto/cpu_arm_linux.c
new file mode 100644
index 0000000..0ffd9a4
--- /dev/null
+++ b/crypto/cpu_arm_linux.c
@@ -0,0 +1,229 @@
+/* Copyright (c) 2016, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <openssl/cpu.h>
+
+#if defined(OPENSSL_ARM) && !defined(OPENSSL_STATIC_ARMCAP)
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <openssl/arm_arch.h>
+#include <openssl/mem.h>
+
+#include "cpu_arm_linux.h"
+
+#define AT_HWCAP 16
+#define AT_HWCAP2 26
+
+// |getauxval| is not available on Android until API level 20. Link it as a weak
+// symbol and use other methods as fallback.
+unsigned long getauxval(unsigned long type) __attribute__((weak));
+
+static int open_eintr(const char *path, int flags) {
+  int ret;
+  do {
+    ret = open(path, flags);
+  } while (ret < 0 && errno == EINTR);
+  return ret;
+}
+
+static ssize_t read_eintr(int fd, void *out, size_t len) {
+  ssize_t ret;
+  do {
+    ret = read(fd, out, len);
+  } while (ret < 0 && errno == EINTR);
+  return ret;
+}
+
+// read_full reads exactly |len| bytes from |fd| to |out|. On error or end of
+// file, it returns zero.
+static int read_full(int fd, void *out, size_t len) {
+  char *outp = out;
+  while (len > 0) {
+    ssize_t ret = read_eintr(fd, outp, len);
+    if (ret <= 0) {
+      return 0;
+    }
+    outp += ret;
+    len -= ret;
+  }
+  return 1;
+}
+
+// read_file opens |path| and reads until end-of-file. On success, it returns
+// one and sets |*out_ptr| and |*out_len| to a newly-allocated buffer with the
+// contents. Otherwise, it returns zero.
+static int read_file(char **out_ptr, size_t *out_len, const char *path) {
+  int fd = open_eintr(path, O_RDONLY);
+  if (fd < 0) {
+    return 0;
+  }
+
+  static const size_t kReadSize = 1024;
+  int ret = 0;
+  size_t cap = kReadSize, len = 0;
+  char *buf = OPENSSL_malloc(cap);
+  if (buf == NULL) {
+    goto err;
+  }
+
+  for (;;) {
+    if (cap - len < kReadSize) {
+      size_t new_cap = cap * 2;
+      if (new_cap < cap) {
+        goto err;
+      }
+      char *new_buf = OPENSSL_realloc(buf, new_cap);
+      if (new_buf == NULL) {
+        goto err;
+      }
+      buf = new_buf;
+      cap = new_cap;
+    }
+
+    ssize_t bytes_read = read_eintr(fd, buf + len, kReadSize);
+    if (bytes_read < 0) {
+      goto err;
+    }
+    if (bytes_read == 0) {
+      break;
+    }
+    len += bytes_read;
+  }
+
+  *out_ptr = buf;
+  *out_len = len;
+  ret = 1;
+  buf = NULL;
+
+err:
+  OPENSSL_free(buf);
+  close(fd);
+  return ret;
+}
+
+// getauxval_proc behaves like |getauxval| but reads from /proc/self/auxv.
+static unsigned long getauxval_proc(unsigned long type) {
+  int fd = open_eintr("/proc/self/auxv", O_RDONLY);
+  if (fd < 0) {
+    return 0;
+  }
+
+  struct {
+    unsigned long tag;
+    unsigned long value;
+  } entry;
+
+  for (;;) {
+    if (!read_full(fd, &entry, sizeof(entry)) ||
+        (entry.tag == 0 && entry.value == 0)) {
+      break;
+    }
+    if (entry.tag == type) {
+      close(fd);
+      return entry.value;
+    }
+  }
+  close(fd);
+  return 0;
+}
+
+extern uint32_t OPENSSL_armcap_P;
+
+static int g_has_broken_neon, g_needs_hwcap2_workaround;
+
+void OPENSSL_cpuid_setup(void) {
+  // We ignore the return value of |read_file| and proceed with an empty
+  // /proc/cpuinfo on error. If |getauxval| works, we will still detect
+  // capabilities. There may be a false positive due to
+  // |crypto_cpuinfo_has_broken_neon|, but this is now rare.
+  char *cpuinfo_data = NULL;
+  size_t cpuinfo_len = 0;
+  read_file(&cpuinfo_data, &cpuinfo_len, "/proc/cpuinfo");
+  STRING_PIECE cpuinfo;
+  cpuinfo.data = cpuinfo_data;
+  cpuinfo.len = cpuinfo_len;
+
+  // |getauxval| is not available on Android until API level 20. If it is
+  // unavailable, read from /proc/self/auxv as a fallback. This is unreadable
+  // on some versions of Android, so further fall back to /proc/cpuinfo.
+  //
+  // See
+  // https://android.googlesource.com/platform/ndk/+/882ac8f3392858991a0e1af33b4b7387ec856bd2
+  // and b/13679666 (Google-internal) for details.
+  unsigned long hwcap = 0;
+  if (getauxval != NULL) {
+    hwcap = getauxval(AT_HWCAP);
+  }
+  if (hwcap == 0) {
+    hwcap = getauxval_proc(AT_HWCAP);
+  }
+  if (hwcap == 0) {
+    hwcap = crypto_get_arm_hwcap_from_cpuinfo(&cpuinfo);
+  }
+
+  // Clear NEON support if known broken. Note, if NEON is available statically,
+  // the non-NEON code is dropped and this workaround is a no-op.
+  //
+  // TODO(davidben): The Android NDK now builds with NEON statically available
+  // by default. Cronet still has some consumers that support NEON-less devices
+  // (b/150371744). Get metrics on whether they still see this CPU and, if not,
+  // remove this check entirely.
+  g_has_broken_neon = crypto_cpuinfo_has_broken_neon(&cpuinfo);
+  if (g_has_broken_neon) {
+    hwcap &= ~HWCAP_NEON;
+  }
+
+  // Matching OpenSSL, only report other features if NEON is present.
+  if (hwcap & HWCAP_NEON) {
+    OPENSSL_armcap_P |= ARMV7_NEON;
+
+    // Some ARMv8 Android devices don't expose AT_HWCAP2. Fall back to
+    // /proc/cpuinfo. See https://crbug.com/boringssl/46. As of February 2021,
+    // this is now rare (see Chrome's Net.NeedsHWCAP2Workaround metric), but AES
+    // and PMULL extensions are very useful, so we still carry the workaround
+    // for now.
+    unsigned long hwcap2 = 0;
+    if (getauxval != NULL) {
+      hwcap2 = getauxval(AT_HWCAP2);
+    }
+    if (hwcap2 == 0) {
+      hwcap2 = crypto_get_arm_hwcap2_from_cpuinfo(&cpuinfo);
+      g_needs_hwcap2_workaround = hwcap2 != 0;
+    }
+
+    if (hwcap2 & HWCAP2_AES) {
+      OPENSSL_armcap_P |= ARMV8_AES;
+    }
+    if (hwcap2 & HWCAP2_PMULL) {
+      OPENSSL_armcap_P |= ARMV8_PMULL;
+    }
+    if (hwcap2 & HWCAP2_SHA1) {
+      OPENSSL_armcap_P |= ARMV8_SHA1;
+    }
+    if (hwcap2 & HWCAP2_SHA2) {
+      OPENSSL_armcap_P |= ARMV8_SHA256;
+    }
+  }
+
+  OPENSSL_free(cpuinfo_data);
+}
+
+int CRYPTO_has_broken_NEON(void) { return g_has_broken_neon; }
+
+int CRYPTO_needs_hwcap2_workaround(void) { return g_needs_hwcap2_workaround; }
+
+#endif  // OPENSSL_ARM && !OPENSSL_STATIC_ARMCAP