diff --git a/doc/ext_ffi_semantics.html b/doc/ext_ffi_semantics.html
index d9aa27c8..b612dbc5 100644
--- a/doc/ext_ffi_semantics.html
+++ b/doc/ext_ffi_semantics.html
@@ -980,8 +980,6 @@ two.</li>
 <li>Calls to non-cdecl or vararg C&nbsp;functions.</li>
 <li>Calls to C&nbsp;functions with aggregates passed or returned by
 value.</li>
-<li>Calls to C&nbsp;functions with 64 bit arguments or return values
-on 32 bit CPUs.</li>
 <li>Calls to ctype metamethods which are not plain functions.</li>
 <li>ctype <tt>__newindex</tt> tables and non-string lookups in ctype
 <tt>__index</tt> tables.</li>
diff --git a/src/lj_asm.c b/src/lj_asm.c
index d5e74185..46142f5c 100644
--- a/src/lj_asm.c
+++ b/src/lj_asm.c
@@ -3346,6 +3346,7 @@ static void asm_hiop(ASMState *as, IRIns *ir)
     break;
     }
   case IR_CALLN:
+  case IR_CALLXS:
     ra_destreg(as, ir, RID_RETHI);
     if (!uselo)
       ra_allocref(as, ir->op1, RID2RSET(RID_RET));  /* Mark call as used. */
diff --git a/src/lj_crecord.c b/src/lj_crecord.c
index 8330faaf..9c93a6f1 100644
--- a/src/lj_crecord.c
+++ b/src/lj_crecord.c
@@ -785,15 +785,16 @@ static int crec_call(jit_State *J, RecordFFData *rd, GCcdata *cd)
 #if LJ_TARGET_X86
 	ctype_cconv(ct->info) != CTCC_CDECL ||
 #endif
-	t == IRT_CDATA || (LJ_32 && (t == IRT_I64 || t == IRT_U64)))
+	t == IRT_CDATA)
       lj_trace_err(J, LJ_TRERR_NYICALL);
     tr = emitir(IRT(IR_CALLXS, t), crec_call_args(J, rd, cts, ct), func);
     if (t == IRT_FLOAT || t == IRT_U32) {
       tr = emitconv(tr, IRT_NUM, t, 0);
     } else if (t == IRT_PTR || (LJ_64 && t == IRT_P32) ||
-	       (LJ_64 && (t == IRT_I64 || t == IRT_U64))) {
+	       (t == IRT_I64 || t == IRT_U64)) {
       TRef trid = lj_ir_kint(J, ctype_cid(ct->info));
       tr = emitir(IRTG(IR_CNEWI, IRT_CDATA), trid, tr);
+      if (t == IRT_I64 || t == IRT_U64) lj_needsplit(J);
     }
     J->base[0] = tr;
     J->needsnap = 1;
diff --git a/src/lj_opt_split.c b/src/lj_opt_split.c
index 90b2b49c..e52ddfd4 100644
--- a/src/lj_opt_split.c
+++ b/src/lj_opt_split.c
@@ -256,6 +256,8 @@ static void split_ir(jit_State *J)
 	}
 	break;
 	}
+      case IR_CALLXS:
+	goto split_call;
       case IR_PHI: {
 	IRRef hiref2;
 	if ((irref_isk(nir->op1) && irref_isk(nir->op2)) ||
@@ -285,6 +287,42 @@ static void split_ir(jit_State *J)
 	  nir->op1 = nir->op2 = 0;
 	}
       }
+    } else if (ir->o == IR_CALLXS) {
+      IRRef hiref;
+    split_call:
+      hiref = hisubst[ir->op1];
+      if (hiref) {
+	IROpT ot = nir->ot;
+	IRRef op2 = nir->op2;
+	nir->ot = IRT(IR_CARG, IRT_NIL);
+#if LJ_LE
+	nir->op2 = hiref;
+#else
+	nir->op2 = nir->op1; nir->op1 = hiref;
+#endif
+	ir->prev = nref = split_emit(J, ot, nref, op2);
+      }
+      if (irt_isint64(ir->t))
+	hi = split_emit(J, IRTI(IR_HIOP), nref, nref);
+    } else if (ir->o == IR_CARG) {
+      IRRef hiref = hisubst[ir->op1];
+      if (hiref) {
+	IRRef op2 = nir->op2;
+#if LJ_LE
+	nir->op2 = hiref;
+#else
+	nir->op2 = nir->op1; nir->op1 = hiref;
+#endif
+	ir->prev = nref = split_emit(J, IRT(IR_CARG, IRT_NIL), nref, op2);
+	nir = IR(nref);
+      }
+      hiref = hisubst[ir->op2];
+      if (hiref) {
+#if LJ_BE
+	IRRef tmp = nir->op2; nir->op2 = hiref; hiref = tmp;
+#endif
+	ir->prev = split_emit(J, IRT(IR_CARG, IRT_NIL), nref, hiref);
+      }
     } else if (ir->o == IR_CNEWI) {
       if (hisubst[ir->op2])
 	split_emit(J, IRT(IR_HIOP, IRT_NIL), nref, hisubst[ir->op2]);