diff --git a/libc/bionic/__cxa_thread_atexit_impl.cpp b/libc/bionic/__cxa_thread_atexit_impl.cpp
index 6284b12..f687fd1 100644
--- a/libc/bionic/__cxa_thread_atexit_impl.cpp
+++ b/libc/bionic/__cxa_thread_atexit_impl.cpp
@@ -15,6 +15,8 @@
  */
 #include <sys/cdefs.h>
 
+#include <private/bionic_defs.h>
+
 #include "pthread_internal.h"
 
 class thread_local_dtor {
@@ -25,7 +27,10 @@
   thread_local_dtor* next;
 };
 
-extern "C" int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle) {
+extern "C" int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle);
+
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
+int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle) {
   thread_local_dtor* dtor = new thread_local_dtor();
 
   dtor->func = func;
diff --git a/libc/bionic/clone.cpp b/libc/bionic/clone.cpp
index 66ec503..b895305 100644
--- a/libc/bionic/clone.cpp
+++ b/libc/bionic/clone.cpp
@@ -34,6 +34,7 @@
 
 #include "pthread_internal.h"
 
+#include "private/bionic_defs.h"
 #include "private/bionic_macros.h"
 
 extern "C" pid_t __bionic_clone(uint32_t flags, void* child_stack, int* parent_tid, void* tls, int* child_tid, int (*fn)(void*), void* arg);
@@ -52,10 +53,11 @@
   __exit(status);
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int clone(int (*fn)(void*), void* child_stack, int flags, void* arg, ...) {
-  int* parent_tid = NULL;
-  void* new_tls = NULL;
-  int* child_tid = NULL;
+  int* parent_tid = nullptr;
+  void* new_tls = nullptr;
+  int* child_tid = nullptr;
 
   if (fn != nullptr && child_stack == nullptr) {
     errno = EINVAL;
diff --git a/libc/bionic/environ.cpp b/libc/bionic/environ.cpp
index 363c1fd..243af62 100644
--- a/libc/bionic/environ.cpp
+++ b/libc/bionic/environ.cpp
@@ -28,6 +28,8 @@
 
 #include <unistd.h>
 
+#include "private/bionic_defs.h"
 // Keep that variable in separate .o file to make sure programs which define
 // their own "environ" are compileable.
+__BIONIC_WEAK_VARIABLE_FOR_NATIVE_BRIDGE
 char** environ;
diff --git a/libc/bionic/fork.cpp b/libc/bionic/fork.cpp
index efcbb8c..33b7343 100644
--- a/libc/bionic/fork.cpp
+++ b/libc/bionic/fork.cpp
@@ -28,8 +28,10 @@
 
 #include <unistd.h>
 
+#include "private/bionic_defs.h"
 #include "pthread_internal.h"
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int fork() {
   __bionic_atfork_run_prepare();
 
diff --git a/libc/bionic/pthread_attr.cpp b/libc/bionic/pthread_attr.cpp
index 0d79374..04d8112 100644
--- a/libc/bionic/pthread_attr.cpp
+++ b/libc/bionic/pthread_attr.cpp
@@ -35,10 +35,12 @@
 
 #include <async_safe/log.h>
 
+#include "private/bionic_defs.h"
 #include "private/bionic_string_utils.h"
 #include "private/ErrnoRestorer.h"
 #include "pthread_internal.h"
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_init(pthread_attr_t* attr) {
   attr->flags = 0;
   attr->stack_base = NULL;
@@ -49,11 +51,13 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_destroy(pthread_attr_t* attr) {
   memset(attr, 0x42, sizeof(pthread_attr_t));
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setinheritsched(pthread_attr_t* attr, int flag) {
   if (flag == PTHREAD_EXPLICIT_SCHED) {
     attr->flags &= ~PTHREAD_ATTR_FLAG_INHERIT;
@@ -65,12 +69,14 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getinheritsched(const pthread_attr_t* attr, int* flag) {
   *flag = (attr->flags & PTHREAD_ATTR_FLAG_INHERIT) ? PTHREAD_INHERIT_SCHED
                                                     : PTHREAD_EXPLICIT_SCHED;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setdetachstate(pthread_attr_t* attr, int state) {
   if (state == PTHREAD_CREATE_DETACHED) {
     attr->flags |= PTHREAD_ATTR_FLAG_DETACHED;
@@ -82,31 +88,37 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getdetachstate(const pthread_attr_t* attr, int* state) {
   *state = (attr->flags & PTHREAD_ATTR_FLAG_DETACHED) ? PTHREAD_CREATE_DETACHED : PTHREAD_CREATE_JOINABLE;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setschedpolicy(pthread_attr_t* attr, int policy) {
   attr->sched_policy = policy;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getschedpolicy(const pthread_attr_t* attr, int* policy) {
   *policy = attr->sched_policy;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setschedparam(pthread_attr_t* attr, const sched_param* param) {
   attr->sched_priority = param->sched_priority;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getschedparam(const pthread_attr_t* attr, sched_param* param) {
   param->sched_priority = attr->sched_priority;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setstacksize(pthread_attr_t* attr, size_t stack_size) {
   if (stack_size < PTHREAD_STACK_MIN) {
     return EINVAL;
@@ -115,11 +127,13 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getstacksize(const pthread_attr_t* attr, size_t* stack_size) {
   void* unused;
   return pthread_attr_getstack(attr, &unused, stack_size);
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setstack(pthread_attr_t* attr, void* stack_base, size_t stack_size) {
   if ((stack_size & (PAGE_SIZE - 1) || stack_size < PTHREAD_STACK_MIN)) {
     return EINVAL;
@@ -198,22 +212,26 @@
   async_safe_fatal("Stack not found in /proc/self/maps");
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getstack(const pthread_attr_t* attr, void** stack_base, size_t* stack_size) {
   *stack_base = attr->stack_base;
   *stack_size = attr->stack_size;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setguardsize(pthread_attr_t* attr, size_t guard_size) {
   attr->guard_size = guard_size;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getguardsize(const pthread_attr_t* attr, size_t* guard_size) {
   *guard_size = attr->guard_size;
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_getattr_np(pthread_t t, pthread_attr_t* attr) {
   pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(t);
   *attr = thread->attr;
@@ -230,6 +248,7 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_setscope(pthread_attr_t*, int scope) {
   if (scope == PTHREAD_SCOPE_SYSTEM) {
     return 0;
@@ -240,6 +259,7 @@
   return EINVAL;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_attr_getscope(const pthread_attr_t*, int* scope) {
   *scope = PTHREAD_SCOPE_SYSTEM;
   return 0;
diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index 11e148c..40db785 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -37,6 +37,7 @@
 
 #include <async_safe/log.h>
 
+#include "private/bionic_defs.h"
 #include "private/bionic_macros.h"
 #include "private/bionic_prctl.h"
 #include "private/bionic_ssp.h"
@@ -258,6 +259,8 @@
   return NULL;
 }
 
+
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
                    void* (*start_routine)(void*), void* arg) {
   ErrnoRestorer errno_restorer;
diff --git a/libc/bionic/pthread_detach.cpp b/libc/bionic/pthread_detach.cpp
index fb8e0dd..011e6c6 100644
--- a/libc/bionic/pthread_detach.cpp
+++ b/libc/bionic/pthread_detach.cpp
@@ -29,8 +29,10 @@
 #include <errno.h>
 #include <pthread.h>
 
+#include "private/bionic_defs.h"
 #include "pthread_internal.h"
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_detach(pthread_t t) {
   pthread_internal_t* thread = __pthread_internal_find(t);
   if (thread == NULL) {
diff --git a/libc/bionic/pthread_exit.cpp b/libc/bionic/pthread_exit.cpp
index ac29c1d..8b4c44e 100644
--- a/libc/bionic/pthread_exit.cpp
+++ b/libc/bionic/pthread_exit.cpp
@@ -33,6 +33,7 @@
 #include <string.h>
 #include <sys/mman.h>
 
+#include "private/bionic_defs.h"
 #include "pthread_internal.h"
 
 extern "C" __noreturn void _exit_with_stack_teardown(void*, size_t);
@@ -44,6 +45,7 @@
  *         and thread cancelation
  */
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 void __pthread_cleanup_push(__pthread_cleanup_t* c, __pthread_cleanup_func_t routine, void* arg) {
   pthread_internal_t* thread = __get_thread();
   c->__cleanup_routine = routine;
@@ -52,6 +54,7 @@
   thread->cleanup_stack = c;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 void __pthread_cleanup_pop(__pthread_cleanup_t* c, int execute) {
   pthread_internal_t* thread = __get_thread();
   thread->cleanup_stack = c->__cleanup_prev;
@@ -60,6 +63,7 @@
   }
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 void pthread_exit(void* return_value) {
   // Call dtors for thread_local objects first.
   __cxa_thread_finalize();
diff --git a/libc/bionic/pthread_gettid_np.cpp b/libc/bionic/pthread_gettid_np.cpp
index fe85442..1beddc9 100644
--- a/libc/bionic/pthread_gettid_np.cpp
+++ b/libc/bionic/pthread_gettid_np.cpp
@@ -26,8 +26,10 @@
  * SUCH DAMAGE.
  */
 
+#include "private/bionic_defs.h"
 #include "pthread_internal.h"
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 pid_t pthread_gettid_np(pthread_t t) {
   pthread_internal_t* thread = __pthread_internal_find(t);
   return thread ? thread->tid : -1;
diff --git a/libc/bionic/pthread_join.cpp b/libc/bionic/pthread_join.cpp
index 4d852cb..be76c20 100644
--- a/libc/bionic/pthread_join.cpp
+++ b/libc/bionic/pthread_join.cpp
@@ -28,9 +28,11 @@
 
 #include <errno.h>
 
+#include "private/bionic_defs.h"
 #include "private/bionic_futex.h"
 #include "pthread_internal.h"
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_join(pthread_t t, void** return_value) {
   if (t == pthread_self()) {
     return EDEADLK;
diff --git a/libc/bionic/pthread_key.cpp b/libc/bionic/pthread_key.cpp
index 6d77afa..baff9cc 100644
--- a/libc/bionic/pthread_key.cpp
+++ b/libc/bionic/pthread_key.cpp
@@ -30,6 +30,7 @@
 #include <pthread.h>
 #include <stdatomic.h>
 
+#include "private/bionic_defs.h"
 #include "private/bionic_tls.h"
 #include "pthread_internal.h"
 
@@ -115,6 +116,7 @@
   }
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_key_create(pthread_key_t* key, void (*key_destructor)(void*)) {
   for (size_t i = 0; i < BIONIC_PTHREAD_KEY_COUNT; ++i) {
     uintptr_t seq = atomic_load_explicit(&key_map[i].seq, memory_order_relaxed);
@@ -133,6 +135,7 @@
 // not call the destructors for non-NULL key values. Instead, it is the
 // responsibility of the caller to properly dispose of the corresponding data
 // and resources, using any means it finds suitable.
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_key_delete(pthread_key_t key) {
   if (__predict_false(!KeyInValidRange(key))) {
     return EINVAL;
@@ -148,6 +151,7 @@
   return EINVAL;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 void* pthread_getspecific(pthread_key_t key) {
   if (__predict_false(!KeyInValidRange(key))) {
     return NULL;
@@ -166,6 +170,7 @@
   return NULL;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_setspecific(pthread_key_t key, const void* ptr) {
   if (__predict_false(!KeyInValidRange(key))) {
     return EINVAL;
diff --git a/libc/bionic/system_properties.cpp b/libc/bionic/system_properties.cpp
index b87d7e8..1a7a359 100644
--- a/libc/bionic/system_properties.cpp
+++ b/libc/bionic/system_properties.cpp
@@ -56,6 +56,7 @@
 #include <async_safe/log.h>
 
 #include "private/ErrnoRestorer.h"
+#include "private/bionic_defs.h"
 #include "private/bionic_futex.h"
 #include "private/bionic_lock.h"
 #include "private/bionic_macros.h"
@@ -254,6 +255,7 @@
 static_assert(sizeof(prop_info) == 96, "size of struct prop_info must be 96 bytes");
 
 // This is public because it was exposed in the NDK. As of 2017-01, ~60 apps reference this symbol.
+__BIONIC_WEAK_VARIABLE_FOR_NATIVE_BRIDGE
 prop_area* __system_property_area__ = nullptr;
 
 static char property_filename[PROP_FILENAME_MAX] = PROP_FILENAME;
@@ -1149,6 +1151,7 @@
   }
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_properties_init() {
   // This is called from __libc_init_common, and should leave errno at 0 (http://b/37248982).
   ErrnoRestorer errno_restorer;
@@ -1177,6 +1180,7 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_set_filename(const char* filename) {
   size_t len = strlen(filename);
   if (len >= sizeof(property_filename)) return -1;
@@ -1185,6 +1189,7 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_area_init() {
   free_and_unmap_contexts();
   mkdir(property_filename, S_IRWXU | S_IXGRP | S_IXOTH);
@@ -1206,6 +1211,7 @@
   return fsetxattr_failed ? -2 : 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 uint32_t __system_property_area_serial() {
   prop_area* pa = __system_property_area__;
   if (!pa) {
@@ -1215,6 +1221,7 @@
   return atomic_load_explicit(pa->serial(), memory_order_acquire);
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 const prop_info* __system_property_find(const char* name) {
   if (!__system_property_area__) {
     return nullptr;
@@ -1233,6 +1240,7 @@
   return strncmp(name, "ro.", 3) == 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_read(const prop_info* pi, char* name, char* value) {
   while (true) {
     uint32_t serial = __system_property_serial(pi);  // acquire semantics
@@ -1270,6 +1278,7 @@
   }
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 void __system_property_read_callback(const prop_info* pi,
                                      void (*callback)(void* cookie,
                                                       const char* name,
@@ -1305,6 +1314,7 @@
   }
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_get(const char* name, char* value) {
   const prop_info* pi = __system_property_find(name);
 
@@ -1341,6 +1351,7 @@
   }
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_set(const char* key, const char* value) {
   if (key == nullptr) return -1;
   if (value == nullptr) value = "";
@@ -1418,6 +1429,7 @@
   }
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_update(prop_info* pi, const char* value, unsigned int len) {
   if (len >= PROP_VALUE_MAX) {
     return -1;
@@ -1448,6 +1460,7 @@
   return 0;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_add(const char* name, unsigned int namelen, const char* value,
                           unsigned int valuelen) {
   if (valuelen >= PROP_VALUE_MAX && !is_read_only(name)) {
@@ -1485,6 +1498,7 @@
 }
 
 // Wait for non-locked serial, and retrieve it with acquire semantics.
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 uint32_t __system_property_serial(const prop_info* pi) {
   uint32_t serial = load_const_atomic(&pi->serial, memory_order_acquire);
   while (SERIAL_DIRTY(serial)) {
@@ -1494,12 +1508,14 @@
   return serial;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 uint32_t __system_property_wait_any(uint32_t old_serial) {
   uint32_t new_serial;
   __system_property_wait(nullptr, old_serial, &new_serial, nullptr);
   return new_serial;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 bool __system_property_wait(const prop_info* pi,
                             uint32_t old_serial,
                             uint32_t* new_serial_ptr,
@@ -1526,6 +1542,7 @@
   return true;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 const prop_info* __system_property_find_nth(unsigned n) {
   struct find_nth {
     const uint32_t sought;
@@ -1542,6 +1559,7 @@
   return state.result;
 }
 
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int __system_property_foreach(void (*propfn)(const prop_info* pi, void* cookie), void* cookie) {
   if (!__system_property_area__) {
     return -1;