diff --git a/configure b/configure
index a499705..91a14c1 100755
--- a/configure
+++ b/configure
@@ -4514,6 +4514,35 @@ EOF
   fi
 fi
 
+#########################################
+# See if 64-bit atomic operations are supported.
+# Note that without __atomic builtins, we can only
+# assume atomic loads/stores max at pointer size.
+
+cat > $TMPC << EOF
+#include <stdint.h>
+int main(void)
+{
+  uint64_t x = 0, y = 0;
+#ifdef __ATOMIC_RELAXED
+  y = __atomic_load_8(&x, 0);
+  __atomic_store_8(&x, y, 0);
+  __atomic_compare_exchange_8(&x, &y, x, 0, 0, 0);
+  __atomic_exchange_8(&x, y, 0);
+  __atomic_fetch_add_8(&x, y, 0);
+#else
+  typedef char is_host64[sizeof(void *) >= sizeof(uint64_t) ? 1 : -1];
+  __sync_lock_test_and_set(&x, y);
+  __sync_val_compare_and_swap(&x, y, 0);
+  __sync_fetch_and_add(&x, y);
+#endif
+  return 0;
+}
+EOF
+if compile_prog "" "" ; then
+  atomic64=yes
+fi
+
 ########################################
 # check if getauxval is available.
 
@@ -5474,6 +5503,10 @@ if test "$atomic128" = "yes" ; then
   echo "CONFIG_ATOMIC128=y" >> $config_host_mak
 fi
 
+if test "$atomic64" = "yes" ; then
+  echo "CONFIG_ATOMIC64=y" >> $config_host_mak
+fi
+
 if test "$getauxval" = "yes" ; then
   echo "CONFIG_GETAUXVAL=y" >> $config_host_mak
 fi
diff --git a/cputlb.c b/cputlb.c
index 845b2a7..cc4da4d 100644
--- a/cputlb.c
+++ b/cputlb.c
@@ -687,8 +687,10 @@ static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
 #define DATA_SIZE 4
 #include "atomic_template.h"
 
+#ifdef CONFIG_ATOMIC64
 #define DATA_SIZE 8
 #include "atomic_template.h"
+#endif
 
 #ifdef CONFIG_ATOMIC128
 #define DATA_SIZE 16
@@ -713,8 +715,10 @@ static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
 #define DATA_SIZE 4
 #include "atomic_template.h"
 
+#ifdef CONFIG_ATOMIC64
 #define DATA_SIZE 8
 #include "atomic_template.h"
+#endif
 
 /* Code access functions.  */
 
diff --git a/tcg-runtime.c b/tcg-runtime.c
index e952153..9327b6f 100644
--- a/tcg-runtime.c
+++ b/tcg-runtime.c
@@ -101,6 +101,11 @@ int64_t HELPER(mulsh_i64)(int64_t arg1, int64_t arg2)
     return h;
 }
 
+void HELPER(exit_atomic)(CPUArchState *env)
+{
+    cpu_loop_exit_atomic(ENV_GET_CPU(env), GETPC());
+}
+
 #ifndef CONFIG_SOFTMMU
 /* The softmmu versions of these helpers are in cputlb.c.  */
 
@@ -130,8 +135,10 @@ static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
 #define DATA_SIZE 4
 #include "atomic_template.h"
 
+#ifdef CONFIG_ATOMIC64
 #define DATA_SIZE 8
 #include "atomic_template.h"
+#endif
 
 /* The following is only callable from other helpers, and matches up
    with the softmmu version.  */
diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index 65e3663..cdd61d6 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -2040,14 +2040,20 @@ typedef void (*gen_atomic_op_i32)(TCGv_i32, TCGv_env, TCGv, TCGv_i32);
 typedef void (*gen_atomic_op_i64)(TCGv_i64, TCGv_env, TCGv, TCGv_i64);
 #endif
 
+#ifdef CONFIG_ATOMIC64
+# define WITH_ATOMIC64(X) X,
+#else
+# define WITH_ATOMIC64(X)
+#endif
+
 static void * const table_cmpxchg[16] = {
     [MO_8] = gen_helper_atomic_cmpxchgb,
     [MO_16 | MO_LE] = gen_helper_atomic_cmpxchgw_le,
     [MO_16 | MO_BE] = gen_helper_atomic_cmpxchgw_be,
     [MO_32 | MO_LE] = gen_helper_atomic_cmpxchgl_le,
     [MO_32 | MO_BE] = gen_helper_atomic_cmpxchgl_be,
-    [MO_64 | MO_LE] = gen_helper_atomic_cmpxchgq_le,
-    [MO_64 | MO_BE] = gen_helper_atomic_cmpxchgq_be,
+    WITH_ATOMIC64([MO_64 | MO_LE] = gen_helper_atomic_cmpxchgq_le)
+    WITH_ATOMIC64([MO_64 | MO_BE] = gen_helper_atomic_cmpxchgq_be)
 };
 
 void tcg_gen_atomic_cmpxchg_i32(TCGv_i32 retv, TCGv addr, TCGv_i32 cmpv,
@@ -2117,6 +2123,7 @@ void tcg_gen_atomic_cmpxchg_i64(TCGv_i64 retv, TCGv addr, TCGv_i64 cmpv,
         }
         tcg_temp_free_i64(t1);
     } else if ((memop & MO_SIZE) == MO_64) {
+#ifdef CONFIG_ATOMIC64
         gen_atomic_cx_i64 gen;
 
         gen = table_cmpxchg[memop & (MO_SIZE | MO_BSWAP)];
@@ -2131,6 +2138,9 @@ void tcg_gen_atomic_cmpxchg_i64(TCGv_i64 retv, TCGv addr, TCGv_i64 cmpv,
 #else
         gen(retv, tcg_ctx.tcg_env, addr, cmpv, newv);
 #endif
+#else
+        gen_helper_exit_atomic(tcg_ctx.tcg_env);
+#endif /* CONFIG_ATOMIC64 */
     } else {
         TCGv_i32 c32 = tcg_temp_new_i32();
         TCGv_i32 n32 = tcg_temp_new_i32();
@@ -2218,6 +2228,7 @@ static void do_atomic_op_i64(TCGv_i64 ret, TCGv addr, TCGv_i64 val,
     memop = tcg_canonicalize_memop(memop, 1, 0);
 
     if ((memop & MO_SIZE) == MO_64) {
+#ifdef CONFIG_ATOMIC64
         gen_atomic_op_i64 gen;
 
         gen = table[memop & (MO_SIZE | MO_BSWAP)];
@@ -2232,6 +2243,9 @@ static void do_atomic_op_i64(TCGv_i64 ret, TCGv addr, TCGv_i64 val,
 #else
         gen(ret, tcg_ctx.tcg_env, addr, val);
 #endif
+#else
+        gen_helper_exit_atomic(tcg_ctx.tcg_env);
+#endif /* CONFIG_ATOMIC64 */
     } else {
         TCGv_i32 v32 = tcg_temp_new_i32();
         TCGv_i32 r32 = tcg_temp_new_i32();
@@ -2256,8 +2270,8 @@ static void * const table_##NAME[16] = {                                \
     [MO_16 | MO_BE] = gen_helper_atomic_##NAME##w_be,                   \
     [MO_32 | MO_LE] = gen_helper_atomic_##NAME##l_le,                   \
     [MO_32 | MO_BE] = gen_helper_atomic_##NAME##l_be,                   \
-    [MO_64 | MO_LE] = gen_helper_atomic_##NAME##q_le,                   \
-    [MO_64 | MO_BE] = gen_helper_atomic_##NAME##q_be,                   \
+    WITH_ATOMIC64([MO_64 | MO_LE] = gen_helper_atomic_##NAME##q_le)     \
+    WITH_ATOMIC64([MO_64 | MO_BE] = gen_helper_atomic_##NAME##q_be)     \
 };                                                                      \
 void tcg_gen_atomic_##NAME##_i32                                        \
     (TCGv_i32 ret, TCGv addr, TCGv_i32 val, TCGArg idx, TCGMemOp memop) \
diff --git a/tcg/tcg-runtime.h b/tcg/tcg-runtime.h
index 22367aa..1deb86a 100644
--- a/tcg/tcg-runtime.h
+++ b/tcg/tcg-runtime.h
@@ -15,23 +15,28 @@ DEF_HELPER_FLAGS_2(sar_i64, TCG_CALL_NO_RWG_SE, s64, s64, s64)
 DEF_HELPER_FLAGS_2(mulsh_i64, TCG_CALL_NO_RWG_SE, s64, s64, s64)
 DEF_HELPER_FLAGS_2(muluh_i64, TCG_CALL_NO_RWG_SE, i64, i64, i64)
 
+DEF_HELPER_FLAGS_1(exit_atomic, TCG_CALL_NO_WG, noreturn, env)
+
 #ifdef CONFIG_SOFTMMU
 
 DEF_HELPER_FLAGS_5(atomic_cmpxchgb, TCG_CALL_NO_WG,
                    i32, env, tl, i32, i32, i32)
 DEF_HELPER_FLAGS_5(atomic_cmpxchgw_be, TCG_CALL_NO_WG,
                    i32, env, tl, i32, i32, i32)
-DEF_HELPER_FLAGS_5(atomic_cmpxchgl_be, TCG_CALL_NO_WG,
-                   i32, env, tl, i32, i32, i32)
-DEF_HELPER_FLAGS_5(atomic_cmpxchgq_be, TCG_CALL_NO_WG,
-                   i64, env, tl, i64, i64, i32)
 DEF_HELPER_FLAGS_5(atomic_cmpxchgw_le, TCG_CALL_NO_WG,
                    i32, env, tl, i32, i32, i32)
+DEF_HELPER_FLAGS_5(atomic_cmpxchgl_be, TCG_CALL_NO_WG,
+                   i32, env, tl, i32, i32, i32)
 DEF_HELPER_FLAGS_5(atomic_cmpxchgl_le, TCG_CALL_NO_WG,
                    i32, env, tl, i32, i32, i32)
+#ifdef CONFIG_ATOMIC64
+DEF_HELPER_FLAGS_5(atomic_cmpxchgq_be, TCG_CALL_NO_WG,
+                   i64, env, tl, i64, i64, i32)
 DEF_HELPER_FLAGS_5(atomic_cmpxchgq_le, TCG_CALL_NO_WG,
                    i64, env, tl, i64, i64, i32)
+#endif
 
+#ifdef CONFIG_ATOMIC64
 #define GEN_ATOMIC_HELPERS(NAME)                                  \
     DEF_HELPER_FLAGS_4(glue(glue(atomic_, NAME), b),              \
                        TCG_CALL_NO_WG, i32, env, tl, i32, i32)    \
@@ -47,17 +52,33 @@ DEF_HELPER_FLAGS_5(atomic_cmpxchgq_le, TCG_CALL_NO_WG,
                        TCG_CALL_NO_WG, i64, env, tl, i64, i32)    \
     DEF_HELPER_FLAGS_4(glue(glue(atomic_, NAME), q_be),           \
                        TCG_CALL_NO_WG, i64, env, tl, i64, i32)
+#else
+#define GEN_ATOMIC_HELPERS(NAME)                                  \
+    DEF_HELPER_FLAGS_4(glue(glue(atomic_, NAME), b),              \
+                       TCG_CALL_NO_WG, i32, env, tl, i32, i32)    \
+    DEF_HELPER_FLAGS_4(glue(glue(atomic_, NAME), w_le),           \
+                       TCG_CALL_NO_WG, i32, env, tl, i32, i32)    \
+    DEF_HELPER_FLAGS_4(glue(glue(atomic_, NAME), w_be),           \
+                       TCG_CALL_NO_WG, i32, env, tl, i32, i32)    \
+    DEF_HELPER_FLAGS_4(glue(glue(atomic_, NAME), l_le),           \
+                       TCG_CALL_NO_WG, i32, env, tl, i32, i32)    \
+    DEF_HELPER_FLAGS_4(glue(glue(atomic_, NAME), l_be),           \
+                       TCG_CALL_NO_WG, i32, env, tl, i32, i32)
+#endif /* CONFIG_ATOMIC64 */
 
 #else
 
 DEF_HELPER_FLAGS_4(atomic_cmpxchgb, TCG_CALL_NO_WG, i32, env, tl, i32, i32)
 DEF_HELPER_FLAGS_4(atomic_cmpxchgw_be, TCG_CALL_NO_WG, i32, env, tl, i32, i32)
-DEF_HELPER_FLAGS_4(atomic_cmpxchgl_be, TCG_CALL_NO_WG, i32, env, tl, i32, i32)
-DEF_HELPER_FLAGS_4(atomic_cmpxchgq_be, TCG_CALL_NO_WG, i64, env, tl, i64, i64)
 DEF_HELPER_FLAGS_4(atomic_cmpxchgw_le, TCG_CALL_NO_WG, i32, env, tl, i32, i32)
+DEF_HELPER_FLAGS_4(atomic_cmpxchgl_be, TCG_CALL_NO_WG, i32, env, tl, i32, i32)
 DEF_HELPER_FLAGS_4(atomic_cmpxchgl_le, TCG_CALL_NO_WG, i32, env, tl, i32, i32)
+#ifdef CONFIG_ATOMIC64
+DEF_HELPER_FLAGS_4(atomic_cmpxchgq_be, TCG_CALL_NO_WG, i64, env, tl, i64, i64)
 DEF_HELPER_FLAGS_4(atomic_cmpxchgq_le, TCG_CALL_NO_WG, i64, env, tl, i64, i64)
+#endif
 
+#ifdef CONFIG_ATOMIC64
 #define GEN_ATOMIC_HELPERS(NAME)                             \
     DEF_HELPER_FLAGS_3(glue(glue(atomic_, NAME), b),         \
                        TCG_CALL_NO_WG, i32, env, tl, i32)    \
@@ -73,6 +94,19 @@ DEF_HELPER_FLAGS_4(atomic_cmpxchgq_le, TCG_CALL_NO_WG, i64, env, tl, i64, i64)
                        TCG_CALL_NO_WG, i64, env, tl, i64)    \
     DEF_HELPER_FLAGS_3(glue(glue(atomic_, NAME), q_be),      \
                        TCG_CALL_NO_WG, i64, env, tl, i64)
+#else
+#define GEN_ATOMIC_HELPERS(NAME)                             \
+    DEF_HELPER_FLAGS_3(glue(glue(atomic_, NAME), b),         \
+                       TCG_CALL_NO_WG, i32, env, tl, i32)    \
+    DEF_HELPER_FLAGS_3(glue(glue(atomic_, NAME), w_le),      \
+                       TCG_CALL_NO_WG, i32, env, tl, i32)    \
+    DEF_HELPER_FLAGS_3(glue(glue(atomic_, NAME), w_be),      \
+                       TCG_CALL_NO_WG, i32, env, tl, i32)    \
+    DEF_HELPER_FLAGS_3(glue(glue(atomic_, NAME), l_le),      \
+                       TCG_CALL_NO_WG, i32, env, tl, i32)    \
+    DEF_HELPER_FLAGS_3(glue(glue(atomic_, NAME), l_be),      \
+                       TCG_CALL_NO_WG, i32, env, tl, i32)
+#endif /* CONFIG_ATOMIC64 */
 
 #endif /* CONFIG_SOFTMMU */
 
diff --git a/tcg/tcg.h b/tcg/tcg.h
index bc3ea7a..b34b5fb 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -1204,14 +1204,23 @@ TYPE helper_atomic_ ## NAME ## SUFFIX ## _mmu         \
     (CPUArchState *env, target_ulong addr, TYPE val,  \
      TCGMemOpIdx oi, uintptr_t retaddr);
 
+#ifdef CONFIG_ATOMIC64
 #define GEN_ATOMIC_HELPER_ALL(NAME)          \
-    GEN_ATOMIC_HELPER(NAME, uint32_t, b)      \
+    GEN_ATOMIC_HELPER(NAME, uint32_t, b)     \
     GEN_ATOMIC_HELPER(NAME, uint32_t, w_le)  \
-    GEN_ATOMIC_HELPER(NAME, uint32_t, l_le)  \
-    GEN_ATOMIC_HELPER(NAME, uint64_t, q_le)  \
     GEN_ATOMIC_HELPER(NAME, uint32_t, w_be)  \
+    GEN_ATOMIC_HELPER(NAME, uint32_t, l_le)  \
     GEN_ATOMIC_HELPER(NAME, uint32_t, l_be)  \
+    GEN_ATOMIC_HELPER(NAME, uint64_t, q_le)  \
     GEN_ATOMIC_HELPER(NAME, uint64_t, q_be)
+#else
+#define GEN_ATOMIC_HELPER_ALL(NAME)          \
+    GEN_ATOMIC_HELPER(NAME, uint32_t, b)     \
+    GEN_ATOMIC_HELPER(NAME, uint32_t, w_le)  \
+    GEN_ATOMIC_HELPER(NAME, uint32_t, w_be)  \
+    GEN_ATOMIC_HELPER(NAME, uint32_t, l_le)  \
+    GEN_ATOMIC_HELPER(NAME, uint32_t, l_be)
+#endif
 
 GEN_ATOMIC_HELPER_ALL(fetch_add)
 GEN_ATOMIC_HELPER_ALL(fetch_sub)
