diff --git a/tcg/s390/tcg-target.c b/tcg/s390/tcg-target.c
index 5b2134b..2b80c02 100644
--- a/tcg/s390/tcg-target.c
+++ b/tcg/s390/tcg-target.c
@@ -40,6 +40,10 @@
    rather than TCG_REG_R0.  */
 #define TCG_REG_NONE    0
 
+/* A scratch register that may be be used throughout the backend.  */
+#define TCG_TMP0        TCG_REG_R13
+
+
 /* All of the following instructions are prefixed with their instruction
    format, and are defined as 8- or 16-bit quantities, even when the two
    halves of the 16-bit quantity may appear 32 bits apart in the insn.
@@ -376,12 +380,12 @@ static inline void tcg_out_movi(TCGContext *s, TCGType type,
         tcg_out_insn(s, RI, IILH, ret, arg >> 16);
     } else {
         /* branch over constant and store its address in R13 */
-        tcg_out_insn(s, RIL, BRASL, TCG_REG_R13, (6 + 8) >> 1);
+        tcg_out_insn(s, RIL, BRASL, TCG_TMP0, (6 + 8) >> 1);
         /* 64-bit constant */
         tcg_out32(s, arg >> 32);
         tcg_out32(s, arg);
         /* load constant to ret */
-        tcg_out_insn(s, RXY, LG, ret, TCG_REG_R13, 0, 0);
+        tcg_out_insn(s, RXY, LG, ret, TCG_TMP0, 0, 0);
     }
 }
 
@@ -399,14 +403,14 @@ static void tcg_out_mem(TCGContext *s, S390Opcode opc_rx, S390Opcode opc_rxy,
     if (ofs < -0x80000 || ofs >= 0x80000) {
         /* Combine the low 16 bits of the offset with the actual load insn;
            the high 48 bits must come from an immediate load.  */
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13, ofs & ~0xffff);
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, ofs & ~0xffff);
         ofs &= 0xffff;
 
         /* If we were already given an index register, add it in.  */
         if (index != TCG_REG_NONE) {
-            tcg_out_insn(s, RRE, AGR, TCG_REG_R13, index);
+            tcg_out_insn(s, RRE, AGR, TCG_TMP0, index);
         }
-        index = TCG_REG_R13;
+        index = TCG_TMP0;
     }
 
     if (opc_rx && ofs >= 0 && ofs < 0x1000) {
@@ -482,8 +486,8 @@ static void tgen_gotoi(TCGContext *s, int cc, tcg_target_long dest)
     } else if (off == (int32_t)off) {
         tcg_out_insn(s, RIL, BRCL, cc, off);
     } else {
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13, dest);
-        tcg_out_insn(s, RR, BCR, cc, TCG_REG_R13);
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, dest);
+        tcg_out_insn(s, RR, BCR, cc, TCG_TMP0);
     }
 }
 
@@ -505,8 +509,8 @@ static void tgen_calli(TCGContext *s, tcg_target_long dest)
     if (off == (int32_t)off) {
         tcg_out_insn(s, RIL, BRASL, TCG_REG_R14, off);
     } else {
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13, dest);
-        tcg_out_insn(s, RR, BASR, TCG_REG_R14, TCG_REG_R13);
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, dest);
+        tcg_out_insn(s, RR, BASR, TCG_REG_R14, TCG_TMP0);
     }
 }
 
@@ -538,22 +542,22 @@ static void tcg_prepare_qemu_ldst(TCGContext* s, int data_reg, int addr_reg,
     tcg_out_sh64(s, RSY_SRLG, arg1, addr_reg, TCG_REG_NONE,
                  TARGET_PAGE_BITS - CPU_TLB_ENTRY_BITS);
 
-    tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13,
+    tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0,
                  TARGET_PAGE_MASK | ((1 << s_bits) - 1));
-    tcg_out_insn(s, RRE, NGR, arg0, TCG_REG_R13);
+    tcg_out_insn(s, RRE, NGR, arg0, TCG_TMP0);
 
-    tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13,
+    tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0,
                  (CPU_TLB_SIZE - 1) << CPU_TLB_ENTRY_BITS);
-    tcg_out_insn(s, RRE, NGR, arg1, TCG_REG_R13);
+    tcg_out_insn(s, RRE, NGR, arg1, TCG_TMP0);
 
     if (is_store) {
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13,
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0,
                      offsetof(CPUState, tlb_table[mem_index][0].addr_write));
     } else {
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13,
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0,
                      offsetof(CPUState, tlb_table[mem_index][0].addr_read));
     }
-    tcg_out_insn(s, RRE, AGR, arg1, TCG_REG_R13);
+    tcg_out_insn(s, RRE, AGR, arg1, TCG_TMP0);
 
     tcg_out_insn(s, RRE, AGR, arg1, TCG_AREG0);
 
@@ -688,8 +692,8 @@ static void tcg_out_qemu_ld(TCGContext* s, const TCGArg* args, int opc)
 #else
         /* swapped unsigned halfword load with upper bits zeroed */
         tcg_out_insn(s, RXY, LRVH, data_reg, arg0, 0, 0);
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13, 0xffffL);
-        tcg_out_insn(s, RRE, NGR, data_reg, 13);
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, 0xffffL);
+        tcg_out_insn(s, RRE, NGR, data_reg, TCG_TMP0);
 #endif
         break;
     case LD_INT16:
@@ -802,16 +806,16 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
                                    (tcg_target_long)s->code_ptr) >> 1;
             if (off == (int32_t)off) {
                 /* load address relative to PC */
-                tcg_out_insn(s, RIL, LARL, TCG_REG_R13, off);
+                tcg_out_insn(s, RIL, LARL, TCG_TMP0, off);
             } else {
                 /* too far for larl */
-                tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R13,
+                tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0,
                              (tcg_target_long)(s->tb_next + args[0]));
             }
             /* load address stored at s->tb_next + args[0] */
-            tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_R13, TCG_REG_R13, 0);
+            tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP0, TCG_TMP0, 0);
             /* and go there */
-            tcg_out_insn(s, RR, BCR, S390_CC_ALWAYS, TCG_REG_R13);
+            tcg_out_insn(s, RR, BCR, S390_CC_ALWAYS, TCG_TMP0);
         }
         s->tb_next_offset[args[0]] = s->code_ptr - s->code_buf;
         break;
@@ -934,9 +938,9 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
         break;
     case INDEX_op_neg_i64:
         /* FIXME: optimize args[0] != args[1] case */
-        tcg_out_mov(s, TCG_REG_R13, args[1]);
+        tcg_out_mov(s, TCG_TMP0, args[1]);
         tcg_out_movi(s, TCG_TYPE_I64, args[0], 0);
-        tcg_out_insn(s, RRE, SGR, args[0], TCG_REG_R13);
+        tcg_out_insn(s, RRE, SGR, args[0], TCG_TMP0);
         break;
 
     case INDEX_op_mul_i32:
@@ -1192,7 +1196,7 @@ void tcg_target_init(TCGContext *s)
 
     tcg_regset_clear(s->reserved_regs);
     /* frequently used as a temporary */
-    tcg_regset_set_reg(s->reserved_regs, TCG_REG_R13);
+    tcg_regset_set_reg(s->reserved_regs, TCG_TMP0);
     /* another temporary */
     tcg_regset_set_reg(s->reserved_regs, TCG_REG_R12);
     /* XXX many insns can't be used with R0, so we better avoid it for now */
