diff --git a/dynasm/dasm_s390x.h b/dynasm/dasm_s390x.h
index 8b43a78c..66dfd79a 100644
--- a/dynasm/dasm_s390x.h
+++ b/dynasm/dasm_s390x.h
@@ -233,8 +233,11 @@ void dasm_put(Dst_DECL, int start, ...)
 	break;
       case DASM_IMM16:
       case DASM_IMM32:
-      case DASM_DISP20:
         fprintf(stderr, "not implemented\n");
+      case DASM_DISP20:
+        CK(-(1<<19) <= n && n < (1<<19), RANGE_I);
+        b[pos++] = n;
+        break;
       case DASM_DISP12:
         CK((n>>12) == 0, RANGE_I);
         b[pos++] = n;
@@ -365,9 +368,12 @@ int dasm_encode(Dst_DECL, void *buffer)
 	case DASM_LABEL_PC: break;
         case DASM_IMM16:
         case DASM_IMM32:
-        case DASM_DISP20:
           fprintf(stderr, "not implemented\n");
           break;
+        case DASM_DISP20:
+          cp[-2] |= n&0xfff;
+          cp[-1] |= (n>>4)&0xff00;
+          break;
         case DASM_DISP12:
           cp[-1] |= n&0xfff;
 	  break;
diff --git a/dynasm/dasm_s390x.lua b/dynasm/dasm_s390x.lua
index b3061653..6900944b 100644
--- a/dynasm/dasm_s390x.lua
+++ b/dynasm/dasm_s390x.lua
@@ -346,8 +346,18 @@ end
 -- and b and x are GPRs.
 -- Encoded as: xblllhh (ls are the low-bits of d, and hs are the high bits).
 local function parse_mem_bxy(arg)
-  werror("parse_mem_bxy: not implemented")
-  return nil
+  local d, x, b = split_memop(arg)
+  local dval = tonumber(d)
+  if dval then
+    if not is_int20(dval) then
+      werror("displacement out of range: ", dval)
+    end
+    return dval, x, b, nil
+  end
+  if match(d, "^[rf]1?[0-9]?") then
+    werror("expected immediate operand, got register")
+  end
+  return 0, x, b, function() waction("DISP20", nil, d) end
 end
 
 local function parse_label(label, def)
@@ -1024,7 +1034,14 @@ local function parse_template(params, template, nparams, pos)
     elseif p == "k" then
 
     elseif p == "l" then
-      
+      local d, x, b, a = parse_mem_bxy(params[2])
+      op0 = op0 + shl(parse_gpr(params[1]), 4) + x
+      op1 = op1 + shl(b, 12) + band(d, 0xfff)
+      op2 = op2 + band(shr(d, 4), 0xff00)
+      wputhw(op0); wputhw(op1); wputhw(op2)
+      if a then
+        a()
+      end
     elseif p == "m" then
       
     elseif p == "n" then