diff --git a/libc/Android.mk b/libc/Android.mk
index ab09089..551c633 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -77,7 +77,6 @@
 	bionic/atol.c \
 	bionic/atoll.c \
 	bionic/bindresvport.c \
-	bionic/bionic_clone.c \
 	bionic/clearenv.c \
 	bionic/daemon.c \
 	bionic/err.c \
@@ -207,6 +206,7 @@
     bionic/brk.cpp \
     bionic/chmod.cpp \
     bionic/chown.cpp \
+    bionic/clone.cpp \
     bionic/dirent.cpp \
     bionic/dup2.cpp \
     bionic/epoll_create.cpp \
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index a027024..c5dc402 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -275,9 +275,6 @@
 int     personality(unsigned long)  all
 long    perf_event_open(struct perf_event_attr* attr_uptr, pid_t pid, int cpu, int group_fd, unsigned long flags) all
 
-pid_t __clone:clone(int, void*, int*, void*, int*)  all
-int __set_tid_address:set_tid_address(int*) all
-
 int epoll_create1(int)  all
 int epoll_ctl(int, int op, int, struct epoll_event*)  all
 int __epoll_pwait:epoll_pwait(int, struct epoll_event*, int, int, const sigset_t*, size_t)  all
@@ -296,6 +293,8 @@
 int __pselect6:pselect6(int, fd_set*, fd_set*, fd_set*, timespec*, void*)  all
 int __ppoll:ppoll(pollfd*, unsigned int, timespec*, const sigset_t*, size_t)  all
 
+int __set_tid_address:set_tid_address(int*)  all
+
 pid_t wait4(pid_t, int*, int, struct rusage*)  all
 int __waitid:waitid(int, pid_t, struct siginfo_t*, int, void*)  all
 
diff --git a/libc/arch-aarch64/syscalls.mk b/libc/arch-aarch64/syscalls.mk
index 890a6d8..ab9c839 100644
--- a/libc/arch-aarch64/syscalls.mk
+++ b/libc/arch-aarch64/syscalls.mk
@@ -1,7 +1,6 @@
 # Generated by gensyscalls.py. Do not edit.
 syscall_src :=
 syscall_src += arch-aarch64/syscalls/__brk.S
-syscall_src += arch-aarch64/syscalls/__clone.S
 syscall_src += arch-aarch64/syscalls/__epoll_pwait.S
 syscall_src += arch-aarch64/syscalls/__exit.S
 syscall_src += arch-aarch64/syscalls/__getcpu.S
diff --git a/libc/arch-aarch64/syscalls/__clone.S b/libc/arch-aarch64/syscalls/__clone.S
deleted file mode 100644
index 45c2022..0000000
--- a/libc/arch-aarch64/syscalls/__clone.S
+++ /dev/null
@@ -1,22 +0,0 @@
-/* Generated by gensyscalls.py. Do not edit. */
-
-#include <private/bionic_asm.h>
-
-ENTRY(__clone)
-    stp     x29, x30, [sp, #-16]!
-    mov     x29,  sp
-    str     x8,       [sp, #-16]!
-
-    mov     x8, __NR_clone
-    svc     #0
-
-    ldr     x8,       [sp], #16
-    ldp     x29, x30, [sp], #16
-
-    cmn     x0, #(MAX_ERRNO + 1)
-    cneg    x0, x0, hi
-    b.hi    __set_errno
-
-    ret
-END(__clone)
-.hidden _C_LABEL(__clone)
diff --git a/libc/arch-arm/arm.mk b/libc/arch-arm/arm.mk
index dea303a..0717306 100644
--- a/libc/arch-arm/arm.mk
+++ b/libc/arch-arm/arm.mk
@@ -1,7 +1,7 @@
 _LIBC_ARCH_COMMON_SRC_FILES := \
     arch-arm/bionic/abort_arm.S \
     arch-arm/bionic/atomics_arm.c \
-    arch-arm/bionic/clone.S \
+    arch-arm/bionic/__bionic_clone.S \
     arch-arm/bionic/eabi.c \
     arch-arm/bionic/_exit_with_stack_teardown.S \
     arch-arm/bionic/futex_arm.S \
diff --git a/libc/arch-arm/bionic/clone.S b/libc/arch-arm/bionic/__bionic_clone.S
similarity index 100%
rename from libc/arch-arm/bionic/clone.S
rename to libc/arch-arm/bionic/__bionic_clone.S
diff --git a/libc/arch-arm/syscalls.mk b/libc/arch-arm/syscalls.mk
index f8bb15a..c0438b4 100644
--- a/libc/arch-arm/syscalls.mk
+++ b/libc/arch-arm/syscalls.mk
@@ -1,7 +1,6 @@
 # Generated by gensyscalls.py. Do not edit.
 syscall_src :=
 syscall_src += arch-arm/syscalls/__brk.S
-syscall_src += arch-arm/syscalls/__clone.S
 syscall_src += arch-arm/syscalls/__epoll_pwait.S
 syscall_src += arch-arm/syscalls/__exit.S
 syscall_src += arch-arm/syscalls/__fcntl64.S
diff --git a/libc/arch-arm/syscalls/__clone.S b/libc/arch-arm/syscalls/__clone.S
deleted file mode 100644
index fb074bc..0000000
--- a/libc/arch-arm/syscalls/__clone.S
+++ /dev/null
@@ -1,17 +0,0 @@
-/* Generated by gensyscalls.py. Do not edit. */
-
-#include <private/bionic_asm.h>
-
-ENTRY(__clone)
-    mov     ip, sp
-    .save   {r4, r5, r6, r7}
-    stmfd   sp!, {r4, r5, r6, r7}
-    ldmfd   ip, {r4, r5, r6}
-    ldr     r7, =__NR_clone
-    swi     #0
-    ldmfd   sp!, {r4, r5, r6, r7}
-    cmn     r0, #(MAX_ERRNO + 1)
-    bxls    lr
-    neg     r0, r0
-    b       __set_errno
-END(__clone)
diff --git a/libc/arch-mips/bionic/clone.S b/libc/arch-mips/bionic/__bionic_clone.S
similarity index 100%
rename from libc/arch-mips/bionic/clone.S
rename to libc/arch-mips/bionic/__bionic_clone.S
diff --git a/libc/arch-mips/mips.mk b/libc/arch-mips/mips.mk
index c895357..1119a66 100644
--- a/libc/arch-mips/mips.mk
+++ b/libc/arch-mips/mips.mk
@@ -1,7 +1,7 @@
 _LIBC_ARCH_COMMON_SRC_FILES := \
+    arch-mips/bionic/__bionic_clone.S \
     arch-mips/bionic/bzero.S \
     arch-mips/bionic/cacheflush.cpp \
-    arch-mips/bionic/clone.S \
     arch-mips/bionic/_exit_with_stack_teardown.S \
     arch-mips/bionic/futex_mips.S \
     arch-mips/bionic/__get_sp.S \
diff --git a/libc/arch-mips/syscalls.mk b/libc/arch-mips/syscalls.mk
index 6b72e70..40932b7 100644
--- a/libc/arch-mips/syscalls.mk
+++ b/libc/arch-mips/syscalls.mk
@@ -1,7 +1,6 @@
 # Generated by gensyscalls.py. Do not edit.
 syscall_src :=
 syscall_src += arch-mips/syscalls/__brk.S
-syscall_src += arch-mips/syscalls/__clone.S
 syscall_src += arch-mips/syscalls/__epoll_pwait.S
 syscall_src += arch-mips/syscalls/__exit.S
 syscall_src += arch-mips/syscalls/__fcntl64.S
diff --git a/libc/arch-mips/syscalls/__clone.S b/libc/arch-mips/syscalls/__clone.S
deleted file mode 100644
index 5ad1489..0000000
--- a/libc/arch-mips/syscalls/__clone.S
+++ /dev/null
@@ -1,23 +0,0 @@
-/* Generated by gensyscalls.py. Do not edit. */
-
-#include <asm/unistd.h>
-    .text
-    .globl __clone
-    .align 4
-    .ent __clone
-
-__clone:
-    .set noreorder
-    .cpload $t9
-    li $v0, __NR_clone
-    syscall
-    bnez $a3, 1f
-    move $a0, $v0
-    j $ra
-    nop
-1:
-    la $t9,__set_errno
-    j $t9
-    nop
-    .set reorder
-    .end __clone
diff --git a/libc/arch-x86/bionic/clone.S b/libc/arch-x86/bionic/__bionic_clone.S
similarity index 100%
rename from libc/arch-x86/bionic/clone.S
rename to libc/arch-x86/bionic/__bionic_clone.S
diff --git a/libc/arch-x86/syscalls.mk b/libc/arch-x86/syscalls.mk
index b6a1e38..780972f 100644
--- a/libc/arch-x86/syscalls.mk
+++ b/libc/arch-x86/syscalls.mk
@@ -1,7 +1,6 @@
 # Generated by gensyscalls.py. Do not edit.
 syscall_src :=
 syscall_src += arch-x86/syscalls/__brk.S
-syscall_src += arch-x86/syscalls/__clone.S
 syscall_src += arch-x86/syscalls/__epoll_pwait.S
 syscall_src += arch-x86/syscalls/__exit.S
 syscall_src += arch-x86/syscalls/__fcntl64.S
diff --git a/libc/arch-x86/syscalls/__clone.S b/libc/arch-x86/syscalls/__clone.S
deleted file mode 100644
index 2ff8fcd..0000000
--- a/libc/arch-x86/syscalls/__clone.S
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Generated by gensyscalls.py. Do not edit. */
-
-#include <private/bionic_asm.h>
-
-ENTRY(__clone)
-    pushl   %ebx
-    pushl   %ecx
-    pushl   %edx
-    pushl   %esi
-    pushl   %edi
-    mov     24(%esp), %ebx
-    mov     28(%esp), %ecx
-    mov     32(%esp), %edx
-    mov     36(%esp), %esi
-    mov     40(%esp), %edi
-    movl    $__NR_clone, %eax
-    int     $0x80
-    cmpl    $-MAX_ERRNO, %eax
-    jb      1f
-    negl    %eax
-    pushl   %eax
-    call    __set_errno
-    addl    $4, %esp
-    orl     $-1, %eax
-1:
-    popl    %edi
-    popl    %esi
-    popl    %edx
-    popl    %ecx
-    popl    %ebx
-    ret
-END(__clone)
diff --git a/libc/arch-x86/x86.mk b/libc/arch-x86/x86.mk
index 5911ad9..9c74084 100644
--- a/libc/arch-x86/x86.mk
+++ b/libc/arch-x86/x86.mk
@@ -1,5 +1,5 @@
 _LIBC_ARCH_COMMON_SRC_FILES := \
-    arch-x86/bionic/clone.S \
+    arch-x86/bionic/__bionic_clone.S \
     arch-x86/bionic/_exit_with_stack_teardown.S \
     arch-x86/bionic/futex_x86.S \
     arch-x86/bionic/__get_sp.S \
diff --git a/libc/arch-x86_64/bionic/clone.S b/libc/arch-x86_64/bionic/__bionic_clone.S
similarity index 91%
rename from libc/arch-x86_64/bionic/clone.S
rename to libc/arch-x86_64/bionic/__bionic_clone.S
index b37416b..309c365 100644
--- a/libc/arch-x86_64/bionic/clone.S
+++ b/libc/arch-x86_64/bionic/__bionic_clone.S
@@ -40,8 +40,13 @@
         movq    %rax, -8(%rsi)  # Write 'arg'.
 
         subq    $16, %rsi
+
+        # Translate to the kernel calling convention and swap the 'tls' and 'child_tid' arguments.
+        # They're flipped for x86-64 compared to all our other architectures and __bionic_clone.
         movq    %r8, %r10
         movq    %rcx, %r8
+
+        # Make the system call.
         movl    $__NR_clone, %eax
         syscall
         testl   %eax, %eax
diff --git a/libc/arch-x86_64/syscalls.mk b/libc/arch-x86_64/syscalls.mk
index 50d9ab3..9e2bfcc 100644
--- a/libc/arch-x86_64/syscalls.mk
+++ b/libc/arch-x86_64/syscalls.mk
@@ -2,7 +2,6 @@
 syscall_src :=
 syscall_src += arch-x86_64/syscalls/__arch_prctl.S
 syscall_src += arch-x86_64/syscalls/__brk.S
-syscall_src += arch-x86_64/syscalls/__clone.S
 syscall_src += arch-x86_64/syscalls/__epoll_pwait.S
 syscall_src += arch-x86_64/syscalls/__exit.S
 syscall_src += arch-x86_64/syscalls/__getcpu.S
diff --git a/libc/arch-x86_64/syscalls/__clone.S b/libc/arch-x86_64/syscalls/__clone.S
deleted file mode 100644
index 4999762..0000000
--- a/libc/arch-x86_64/syscalls/__clone.S
+++ /dev/null
@@ -1,18 +0,0 @@
-/* Generated by gensyscalls.py. Do not edit. */
-
-#include <private/bionic_asm.h>
-
-ENTRY(__clone)
-    movq    %rcx, %r10
-    movl    $__NR_clone, %eax
-    syscall
-    cmpq    $-MAX_ERRNO, %rax
-    jb      1f
-    negl    %eax
-    movl    %eax, %edi
-    call    __set_errno
-    orq     $-1, %rax
-1:
-    ret
-END(__clone)
-.hidden _C_LABEL(__clone)
diff --git a/libc/arch-x86_64/x86_64.mk b/libc/arch-x86_64/x86_64.mk
index 4f833c1..2614537 100644
--- a/libc/arch-x86_64/x86_64.mk
+++ b/libc/arch-x86_64/x86_64.mk
@@ -1,5 +1,5 @@
 _LIBC_ARCH_COMMON_SRC_FILES := \
-    arch-x86_64/bionic/clone.S \
+    arch-x86_64/bionic/__bionic_clone.S \
     arch-x86_64/bionic/_exit_with_stack_teardown.S \
     arch-x86_64/bionic/futex_x86_64.S \
     arch-x86_64/bionic/__get_sp.S \
diff --git a/libc/bionic/bionic_clone.c b/libc/bionic/clone.cpp
similarity index 61%
rename from libc/bionic/bionic_clone.c
rename to libc/bionic/clone.cpp
index 518d996..1d997fe 100644
--- a/libc/bionic/bionic_clone.c
+++ b/libc/bionic/clone.cpp
@@ -25,41 +25,39 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #define __GNU_SOURCE 1
 #include <sched.h>
 #include <stdlib.h>
 #include <stdarg.h>
-#include <stdio.h>
 
-extern pid_t __bionic_clone(uint32_t flags, void* child_stack, int* parent_tid, void* tls, int* child_tid, int (*fn)(void*), void* arg);
-extern void __exit(int status);
+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);
+extern "C" void __exit(int status);
 
-/* this function is called from the __bionic_clone
- * assembly fragment to call the thread function
- * then exit. */
-extern void __bionic_clone_entry(int (*fn)(void*), void* arg) {
+// Called from the __bionic_clone assembler to call the thread function then exit.
+extern "C" void __bionic_clone_entry(int (*fn)(void*), void* arg) {
   int status = (*fn)(arg);
   __exit(status);
 }
 
 int clone(int (*fn)(void*), void* child_stack, int flags, void* arg, ...) {
-    va_list  args;
-    int     *parent_tidptr = NULL;
-    void    *new_tls = NULL;
-    int     *child_tidptr = NULL;
+  int* parent_tid = NULL;
+  void* new_tls = NULL;
+  int* child_tid = NULL;
 
-    /* extract optional parameters - they are cumulative. */
-    va_start(args, arg);
-    if (flags & (CLONE_PARENT_SETTID|CLONE_SETTLS|CLONE_CHILD_SETTID)) {
-        parent_tidptr = va_arg(args, int*);
-    }
-    if (flags & (CLONE_SETTLS|CLONE_CHILD_SETTID)) {
-        new_tls = va_arg(args, void*);
-    }
-    if (flags & CLONE_CHILD_SETTID) {
-        child_tidptr = va_arg(args, int*);
-    }
-    va_end(args);
+  // Extract any optional parameters required by the flags.
+  va_list args;
+  va_start(args, arg);
+  if ((flags & (CLONE_PARENT_SETTID|CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
+    parent_tid = va_arg(args, int*);
+  }
+  if ((flags & (CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
+    new_tls = va_arg(args, void*);
+  }
+  if ((flags & (CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
+    child_tid = va_arg(args, int*);
+  }
+  va_end(args);
 
-    return __bionic_clone(flags, child_stack, parent_tidptr, new_tls, child_tidptr, fn, arg);
+  return __bionic_clone(flags, child_stack, parent_tid, new_tls, child_tid, fn, arg);
 }
diff --git a/libc/bionic/fork.cpp b/libc/bionic/fork.cpp
index f7d1c11..9fa5fcf 100644
--- a/libc/bionic/fork.cpp
+++ b/libc/bionic/fork.cpp
@@ -27,12 +27,11 @@
  */
 
 #include <unistd.h>
+#include <sys/syscall.h>
+
+#include "private/libc_logging.h"
 #include "pthread_internal.h"
 
-#include "private/bionic_pthread.h"
-
-extern "C" int __clone(int, void*, int*, void*, int*);
-
 int fork() {
   // POSIX mandates that the timers of a fork child process be
   // disarmed, but not destroyed. To avoid a race condition, we're
@@ -42,18 +41,17 @@
   __bionic_atfork_run_prepare();
 
   pthread_internal_t* self = __get_thread();
-#if defined(__x86_64__)
-  int result = __clone(CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD, NULL, NULL, &(self->tid), NULL);
+  int flags = CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD;
+#if defined(__x86_64__) // sys_clone's last two arguments are flipped on x86-64.
+  int result = syscall(__NR_clone, flags, NULL, NULL, &(self->tid), NULL);
 #else
-  int result = __clone(CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD, NULL, NULL, NULL, &(self->tid));
+  int result = syscall(__NR_clone, flags, NULL, NULL, NULL, &(self->tid));
 #endif
-  if (result != 0) {  // Not a child process.
+  if (result == 0) {
+    __bionic_atfork_run_child();
+  } else {
     __timer_table_start_stop(0);
     __bionic_atfork_run_parent();
-  } else {
-    // Fix the tid in the pthread_internal_t struct after a fork.
-    __pthread_settid(pthread_self(), gettid());
-    __bionic_atfork_run_child();
   }
   return result;
 }
diff --git a/libc/bionic/pthread_cond.cpp b/libc/bionic/pthread_cond.cpp
index abd453e..7c229b5 100644
--- a/libc/bionic/pthread_cond.cpp
+++ b/libc/bionic/pthread_cond.cpp
@@ -38,7 +38,6 @@
 
 #include "private/bionic_atomic_inline.h"
 #include "private/bionic_futex.h"
-#include "private/bionic_pthread.h"
 #include "private/bionic_time_conversions.h"
 #include "private/bionic_tls.h"
 #include "private/thread_private.h"
diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index de1ef26..bcd9b71 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -97,6 +97,5 @@
 __LIBC_HIDDEN__ extern void __bionic_atfork_run_prepare();
 __LIBC_HIDDEN__ extern void __bionic_atfork_run_child();
 __LIBC_HIDDEN__ extern void __bionic_atfork_run_parent();
-__LIBC_HIDDEN__ extern int __pthread_settid(pthread_t, pid_t);
 
 #endif /* _PTHREAD_INTERNAL_H_ */
diff --git a/libc/bionic/pthread_internals.cpp b/libc/bionic/pthread_internals.cpp
index 4b1f6ef..f8afeaf 100644
--- a/libc/bionic/pthread_internals.cpp
+++ b/libc/bionic/pthread_internals.cpp
@@ -73,14 +73,6 @@
   return reinterpret_cast<pthread_internal_t*>(t)->tid;
 }
 
-int __pthread_settid(pthread_t t, pid_t tid) {
-  if (t == 0) {
-    return EINVAL;
-  }
-  reinterpret_cast<pthread_internal_t*>(t)->tid = tid;
-  return 0;
-}
-
 // Initialize 'ts' with the difference between 'abstime' and the current time
 // according to 'clock'. Returns -1 if abstime already expired, or 0 otherwise.
 int __timespec_to_absolute(timespec* ts, const timespec* abstime, clockid_t clock) {
diff --git a/libc/bionic/pthread_mutex.cpp b/libc/bionic/pthread_mutex.cpp
index 7e43cd8..1010f11 100644
--- a/libc/bionic/pthread_mutex.cpp
+++ b/libc/bionic/pthread_mutex.cpp
@@ -38,7 +38,6 @@
 
 #include "private/bionic_atomic_inline.h"
 #include "private/bionic_futex.h"
-#include "private/bionic_pthread.h"
 #include "private/bionic_tls.h"
 #include "private/thread_private.h"