diff --git a/target-i386/helper.h b/target-i386/helper.h
index 729d4b63da57..4e859eba9d46 100644
--- a/target-i386/helper.h
+++ b/target-i386/helper.h
@@ -1,8 +1,6 @@
 DEF_HELPER_FLAGS_4(cc_compute_all, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int)
 DEF_HELPER_FLAGS_4(cc_compute_c, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int)
 
-DEF_HELPER_0(lock, void)
-DEF_HELPER_0(unlock, void)
 DEF_HELPER_3(write_eflags, void, env, tl, i32)
 DEF_HELPER_1(read_eflags, tl, env)
 DEF_HELPER_2(divb_AL, void, env, tl)
diff --git a/target-i386/mem_helper.c b/target-i386/mem_helper.c
index c4b5c5bd94c7..70f67668ab26 100644
--- a/target-i386/mem_helper.c
+++ b/target-i386/mem_helper.c
@@ -25,39 +25,6 @@
 #include "qemu/int128.h"
 #include "tcg.h"
 
-/* broken thread support */
-
-#if defined(CONFIG_USER_ONLY)
-QemuMutex global_cpu_lock;
-
-void helper_lock(void)
-{
-    qemu_mutex_lock(&global_cpu_lock);
-}
-
-void helper_unlock(void)
-{
-    qemu_mutex_unlock(&global_cpu_lock);
-}
-
-void helper_lock_init(void)
-{
-    qemu_mutex_init(&global_cpu_lock);
-}
-#else
-void helper_lock(void)
-{
-}
-
-void helper_unlock(void)
-{
-}
-
-void helper_lock_init(void)
-{
-}
-#endif
-
 void helper_cmpxchg8b_unlocked(CPUX86State *env, target_ulong a0)
 {
     uintptr_t ra = GETPC();
diff --git a/target-i386/translate.c b/target-i386/translate.c
index cfa395654322..927b3665341f 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -4536,10 +4536,6 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
     s->aflag = aflag;
     s->dflag = dflag;
 
-    /* lock generation */
-    if (prefixes & PREFIX_LOCK)
-        gen_helper_lock();
-
     /* now check op code */
  reswitch:
     switch(b) {
@@ -8211,20 +8207,11 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
     default:
         goto unknown_op;
     }
-    /* lock generation */
-    if (s->prefix & PREFIX_LOCK)
-        gen_helper_unlock();
     return s->pc;
  illegal_op:
-    if (s->prefix & PREFIX_LOCK)
-        gen_helper_unlock();
-    /* XXX: ensure that no lock was generated */
     gen_illegal_opcode(s);
     return s->pc;
  unknown_op:
-    if (s->prefix & PREFIX_LOCK)
-        gen_helper_unlock();
-    /* XXX: ensure that no lock was generated */
     gen_unknown_opcode(env, s);
     return s->pc;
 }
@@ -8316,8 +8303,6 @@ void tcg_x86_init(void)
                                      offsetof(CPUX86State, bnd_regs[i].ub),
                                      bnd_regu_names[i]);
     }
-
-    helper_lock_init();
 }
 
 /* generate intermediate code for basic block 'tb'.  */