diff --git a/libc/arch-arm/dynamic_function_dispatch.cpp b/libc/arch-arm/dynamic_function_dispatch.cpp
new file mode 100644
index 0000000..17f0087
--- /dev/null
+++ b/libc/arch-arm/dynamic_function_dispatch.cpp
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <fcntl.h>
+#include <sys/syscall.h>
+
+extern "C" {
+
+enum CpuVariant {
+    kUnknown = 0,
+    kGeneric,
+    kCortexA7,
+    kCortexA9,
+    kCortexA53,
+    kCortexA55,
+    kDenver,
+    kKrait,
+    kKryo,
+};
+
+static constexpr int MAX_CPU_NAME_LEN = 12;
+struct CpuVariantNames {
+    char name[MAX_CPU_NAME_LEN];
+    CpuVariant variant;
+};
+
+static constexpr CpuVariantNames cpu_variant_names[] = {
+    {"cortex-a76", kCortexA55},
+    {"cortex-a75", kCortexA55},
+    {"kryo", kKryo},
+    {"cortex-a73", kCortexA55},
+    {"cortex-a55", kCortexA55},
+    {"cortex-a53", kCortexA53},
+    {"krait", kKrait},
+    {"cortex-a9", kCortexA9},
+    {"cortex-a7", kCortexA7},
+    {"denver", kDenver},
+    // kUnknown indicates the end of this array.
+    {"", kUnknown},
+};
+
+static long ifunc_open(const char* pathname) {
+    register long r0 __asm__("r0") = AT_FDCWD;
+    register long r1 __asm__("r1") = reinterpret_cast<long>(pathname);
+    register long r2 __asm__("r2") = O_RDONLY;
+    register long r3 __asm__("r3") = 0;
+    register long r7 __asm__("r7") = __NR_openat;
+    __asm__ volatile("swi #0" : "=r"(r0) : "r"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r7));
+    return r0;
+}
+
+static ssize_t ifunc_read(int fd, void* buf, size_t count) {
+    register long r0 __asm__("r0") = fd;
+    register long r1 __asm__("r1") = reinterpret_cast<long>(buf);
+    register long r2 __asm__("r2") = count;
+    register long r7 __asm__("r7") = __NR_read;
+    __asm__ volatile("swi #0" : "=r"(r0) : "r"(r0), "r"(r1), "r"(r2), "r"(r7) : "memory");
+    return r0;
+}
+
+static int ifunc_close(int fd) {
+    register long r0 __asm__("r0") = fd;
+    register long r7 __asm__("r7") = __NR_close;
+    __asm__ volatile("swi #0" : "=r"(r0) : "r"(r0), "r"(r7));
+    return r0;
+}
+
+#define DEFINE_IFUNC(name) \
+    name##_func name __attribute__((ifunc(#name "_resolver"))); \
+    __attribute__((visibility("hidden"))) \
+    name##_func* name##_resolver()
+
+#define DECLARE_FUNC(type, name) \
+    __attribute__((visibility("hidden"))) \
+    type name
+
+#define RETURN_FUNC(type, name) { \
+        DECLARE_FUNC(type, name); \
+        return name; \
+    }
+
+static CpuVariant init_cpu_variant() {
+    int fd = ifunc_open("/dev/cpu_variant:arm");
+    if (fd < 0) return kGeneric;
+
+    char name[MAX_CPU_NAME_LEN];
+
+    int bytes_read, total_read = 0;
+    while (total_read < MAX_CPU_NAME_LEN - 1 &&
+           (bytes_read = ifunc_read(fd, name + total_read,
+                                    MAX_CPU_NAME_LEN - 1 - total_read)) > 0) {
+        total_read += bytes_read;
+    }
+    ifunc_close(fd);
+
+    if (bytes_read != 0) {
+        // The file is too big. We haven't reach the end. Or maybe there is an
+        // error when reading.
+        return kGeneric;
+    }
+    name[total_read] = 0;
+
+    typedef int strcmp_func(const char* __lhs, const char* __rhs);
+    DECLARE_FUNC(strcmp_func, strcmp_a15);
+
+    const CpuVariantNames* cpu_variant = cpu_variant_names;
+    while (cpu_variant->variant != kUnknown) {
+        if (strcmp_a15(cpu_variant->name, name) == 0) {
+            return cpu_variant->variant;
+        }
+        cpu_variant++;
+    }
+    return kGeneric;
+}
+
+static CpuVariant get_cpu_variant() {
+    static CpuVariant cpu_variant = kUnknown;
+    if (cpu_variant == kUnknown) {
+        cpu_variant = init_cpu_variant();
+    }
+    return cpu_variant;
+}
+
+typedef void* memmove_func(void* __dst, const void* __src, size_t __n);
+DEFINE_IFUNC(memmove) {
+    switch(get_cpu_variant()) {
+        case kCortexA7:
+            RETURN_FUNC(memmove_func, memmove_a7);
+        case kCortexA9:
+            RETURN_FUNC(memmove_func, memmove_a9);
+        case kKrait:
+            RETURN_FUNC(memmove_func, memmove_krait);
+        case kCortexA53:
+            RETURN_FUNC(memmove_func, memmove_a53);
+        case kCortexA55:
+        case kDenver:
+            RETURN_FUNC(memmove_func, memmove_denver);
+        case kKryo:
+            RETURN_FUNC(memmove_func, memmove_kryo);
+        default:
+            RETURN_FUNC(memmove_func, memmove_a15);
+    }
+}
+
+typedef void* memcpy_func(void*, const void*, size_t);
+DEFINE_IFUNC(memcpy) {
+    return memmove_resolver();
+}
+
+typedef void* __memset_chk_func(void* s, int c, size_t n, size_t n2);
+DEFINE_IFUNC(__memset_chk) {
+    switch(get_cpu_variant()) {
+        case kCortexA7:
+        case kCortexA53:
+        case kCortexA55:
+        case kKryo:
+            RETURN_FUNC(__memset_chk_func, __memset_chk_a7);
+        case kCortexA9:
+            RETURN_FUNC(__memset_chk_func, __memset_chk_a9);
+        case kKrait:
+            RETURN_FUNC(__memset_chk_func, __memset_chk_krait);
+        case kDenver:
+            RETURN_FUNC(__memset_chk_func, __memset_chk_denver);
+        default:
+            RETURN_FUNC(__memset_chk_func, __memset_chk_a15);
+    }
+}
+
+typedef void* memset_func(void* __dst, int __ch, size_t __n);
+DEFINE_IFUNC(memset) {
+    switch(get_cpu_variant()) {
+        case kCortexA7:
+        case kCortexA53:
+        case kCortexA55:
+        case kKryo:
+             RETURN_FUNC(memset_func, memset_a7);
+        case kCortexA9:
+             RETURN_FUNC(memset_func, memset_a9);
+        case kKrait:
+             RETURN_FUNC(memset_func, memset_krait);
+        case kDenver:
+             RETURN_FUNC(memset_func, memset_denver);
+        default:
+             RETURN_FUNC(memset_func, memset_a15);
+    }
+}
+
+typedef char* strcpy_func(char* __dst, const char* __src);
+DEFINE_IFUNC(strcpy) {
+    switch(get_cpu_variant()) {
+        case kCortexA9:
+            RETURN_FUNC(strcpy_func, strcpy_a9);
+        default:
+            RETURN_FUNC(strcpy_func, strcpy_a15);
+    }
+}
+
+typedef char* stpcpy_func(char* __dst, const char* __src);
+DEFINE_IFUNC(stpcpy) {
+    switch(get_cpu_variant()) {
+        case kCortexA9:
+            RETURN_FUNC(stpcpy_func, stpcpy_a9);
+        default:
+            RETURN_FUNC(stpcpy_func, stpcpy_a15);
+    }
+}
+
+typedef char* strcat_func(char* __dst, const char* __src);
+DEFINE_IFUNC(strcat) {
+    switch(get_cpu_variant()) {
+        case kCortexA9:
+            RETURN_FUNC(strcat_func, strcat_a9);
+        default:
+            RETURN_FUNC(strcat_func, strcat_a15);
+    }
+}
+
+typedef int strcmp_func(const char* __lhs, const char* __rhs);
+DEFINE_IFUNC(strcmp) {
+    switch(get_cpu_variant()) {
+        case kCortexA9:
+            RETURN_FUNC(strcmp_func, strcmp_a9);
+        case kCortexA55:
+        case kKrait:
+        case kKryo:
+            RETURN_FUNC(strcmp_func, strcmp_krait);
+        default:
+            RETURN_FUNC(strcmp_func, strcmp_a15);
+    }
+}
+
+typedef size_t strlen_func(const char* __s);
+DEFINE_IFUNC(strlen) {
+    switch(get_cpu_variant()) {
+        case kCortexA9:
+            RETURN_FUNC(strlen_func, strlen_a9);
+        default:
+            RETURN_FUNC(strlen_func, strlen_a15);
+    }
+}
+
+}  // extern "C"