diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 83c32c4dac..e30020c8e9 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -666,35 +666,55 @@ uint32_t HELPER(clcle)(CPUS390XState *env, uint32_t r1, uint64_t a2,
                        uint32_t r3)
 {
     uintptr_t ra = GETPC();
-    uint64_t destlen = get_length(env, r1 + 1);
-    uint64_t dest = get_address(env, r1);
-    uint64_t srclen = get_length(env, r3 + 1);
-    uint64_t src = get_address(env, r3);
+    uint64_t src1len = get_length(env, r1 + 1);
+    uint64_t src1 = get_address(env, r1);
+    uint64_t src3len = get_length(env, r3 + 1);
+    uint64_t src3 = get_address(env, r3);
     uint8_t pad = a2 & 0xff;
+    uint64_t len = MAX(src1len, src3len);
     uint32_t cc = 0;
 
-    if (!(destlen || srclen)) {
+    if (!len) {
         return cc;
     }
 
-    if (srclen > destlen) {
-        srclen = destlen;
+    /* Lest we fail to service interrupts in a timely manner, limit the
+       amount of work we're willing to do.  For now, let's cap at 8k.  */
+    if (len > 0x2000) {
+        len = 0x2000;
+        cc = 3;
     }
 
-    for (; destlen || srclen; src++, dest++, destlen--, srclen--) {
-        uint8_t v1 = srclen ? cpu_ldub_data_ra(env, src, ra) : pad;
-        uint8_t v2 = destlen ? cpu_ldub_data_ra(env, dest, ra) : pad;
-        if (v1 != v2) {
-            cc = (v1 < v2) ? 1 : 2;
+    for (; len; len--) {
+        uint8_t v1 = pad;
+        uint8_t v3 = pad;
+
+        if (src1len) {
+            v1 = cpu_ldub_data_ra(env, src1, ra);
+        }
+        if (src3len) {
+            v3 = cpu_ldub_data_ra(env, src3, ra);
+        }
+
+        if (v1 != v3) {
+            cc = (v1 < v3) ? 1 : 2;
             break;
         }
+
+        if (src1len) {
+            src1++;
+            src1len--;
+        }
+        if (src3len) {
+            src3++;
+            src3len--;
+        }
     }
 
-    set_length(env, r1 + 1, destlen);
-    /* can't use srclen here, we trunc'ed it */
-    set_length(env, r3 + 1, env->regs[r3 + 1] - src - env->regs[r3]);
-    set_address(env, r1, dest);
-    set_address(env, r3, src);
+    set_length(env, r1 + 1, src1len);
+    set_length(env, r3 + 1, src3len);
+    set_address(env, r1, src1);
+    set_address(env, r3, src3);
 
     return cc;
 }
diff --git a/target/s390x/translate.c b/target/s390x/translate.c
index a21de0967a..ecd0a91c04 100644
--- a/target/s390x/translate.c
+++ b/target/s390x/translate.c
@@ -1922,11 +1922,21 @@ static ExitStatus op_clc(DisasContext *s, DisasOps *o)
 
 static ExitStatus op_clcle(DisasContext *s, DisasOps *o)
 {
-    TCGv_i32 r1 = tcg_const_i32(get_field(s->fields, r1));
-    TCGv_i32 r3 = tcg_const_i32(get_field(s->fields, r3));
-    gen_helper_clcle(cc_op, cpu_env, r1, o->in2, r3);
-    tcg_temp_free_i32(r1);
-    tcg_temp_free_i32(r3);
+    int r1 = get_field(s->fields, r1);
+    int r3 = get_field(s->fields, r3);
+    TCGv_i32 t1, t3;
+
+    /* r1 and r3 must be even.  */
+    if (r1 & 1 || r3 & 1) {
+        gen_program_exception(s, PGM_SPECIFICATION);
+        return EXIT_NORETURN;
+    }
+
+    t1 = tcg_const_i32(r1);
+    t3 = tcg_const_i32(r3);
+    gen_helper_clcle(cc_op, cpu_env, t1, o->in2, t3);
+    tcg_temp_free_i32(t1);
+    tcg_temp_free_i32(t3);
     set_cc_static(s);
     return NO_EXIT;
 }