diff --git a/src/debug/s390/debug-s390.cc b/src/debug/s390/debug-s390.cc
new file mode 100644
index 0000000..c6764c2
--- /dev/null
+++ b/src/debug/s390/debug-s390.cc
@@ -0,0 +1,165 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/v8.h"
+
+#if V8_TARGET_ARCH_S390
+
+#include "src/codegen.h"
+#include "src/debug/debug.h"
+
+namespace v8 {
+namespace internal {
+
+#define __ ACCESS_MASM(masm)
+
+void EmitDebugBreakSlot(MacroAssembler* masm) {
+  Label check_size;
+  __ bind(&check_size);
+  //   oill r3, 0
+  //   oill r3, 0
+  __ nop(Assembler::DEBUG_BREAK_NOP);
+  __ nop(Assembler::DEBUG_BREAK_NOP);
+
+  //   lr r0, r0    64-bit only
+  //   lr r0, r0    64-bit only
+  //   lr r0, r0    64-bit only
+  for (int i = 8; i < Assembler::kDebugBreakSlotLength; i += 2) {
+    __ nop();
+  }
+  DCHECK_EQ(Assembler::kDebugBreakSlotLength,
+            masm->SizeOfCodeGeneratedSince(&check_size));
+}
+
+void DebugCodegen::GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode) {
+  // Generate enough nop's to make space for a call instruction.
+  masm->RecordDebugBreakSlot(mode);
+  EmitDebugBreakSlot(masm);
+}
+
+void DebugCodegen::ClearDebugBreakSlot(Isolate* isolate, Address pc) {
+  CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotLength);
+  EmitDebugBreakSlot(patcher.masm());
+}
+
+void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
+                                       Handle<Code> code) {
+  DCHECK_EQ(Code::BUILTIN, code->kind());
+  CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotLength);
+  // Patch the code changing the debug break slot code from
+  //
+  //   oill r3, 0
+  //   oill r3, 0
+  //   oill r3, 0   64-bit only
+  //   lr r0, r0    64-bit only
+  //
+  // to a call to the debug break code, using a FIXED_SEQUENCE.
+  //
+  //   iilf r14, <address>   6-bytes
+  //   basr r14, r14A        2-bytes
+  //
+  // The 64bit sequence has an extra iihf.
+  //
+  //   iihf r14, <high 32-bits address>    6-bytes
+  //   iilf r14, <lower 32-bits address>   6-bytes
+  //   basr r14, r14                       2-bytes
+  patcher.masm()->mov(v8::internal::r14,
+                      Operand(reinterpret_cast<intptr_t>(code->entry())));
+  patcher.masm()->basr(v8::internal::r14, v8::internal::r14);
+}
+
+bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
+  Instr current_instr = Assembler::instr_at(pc);
+  return !Assembler::IsNop(current_instr, Assembler::DEBUG_BREAK_NOP);
+}
+
+void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
+                                          DebugBreakCallHelperMode mode) {
+  __ RecordComment("Debug break");
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+
+    // Load padding words on stack.
+    __ LoadSmiLiteral(ip, Smi::FromInt(LiveEdit::kFramePaddingValue));
+    for (int i = 0; i < LiveEdit::kFramePaddingInitialSize; i++) {
+      __ push(ip);
+    }
+    __ LoadSmiLiteral(ip, Smi::FromInt(LiveEdit::kFramePaddingInitialSize));
+    __ push(ip);
+
+    // Push arguments for DebugBreak call.
+    if (mode == SAVE_RESULT_REGISTER) {
+      // Break on return.
+      __ push(r2);
+    } else {
+      // Non-return breaks.
+      __ Push(masm->isolate()->factory()->the_hole_value());
+    }
+    __ mov(r2, Operand(1));
+    __ mov(r3,
+           Operand(ExternalReference(
+               Runtime::FunctionForId(Runtime::kDebugBreak), masm->isolate())));
+
+    CEntryStub ceb(masm->isolate(), 1);
+    __ CallStub(&ceb);
+
+    if (FLAG_debug_code) {
+      for (int i = 0; i < kNumJSCallerSaved; i++) {
+        Register reg = {JSCallerSavedCode(i)};
+        // Do not clobber r2 if mode is SAVE_RESULT_REGISTER. It will
+        // contain return value of the function.
+        if (!(reg.is(r2) && (mode == SAVE_RESULT_REGISTER))) {
+          __ mov(reg, Operand(kDebugZapValue));
+        }
+      }
+    }
+
+    // Don't bother removing padding bytes pushed on the stack
+    // as the frame is going to be restored right away.
+
+    // Leave the internal frame.
+  }
+
+  // Now that the break point has been handled, resume normal execution by
+  // jumping to the target address intended by the caller and that was
+  // overwritten by the address of DebugBreakXXX.
+  ExternalReference after_break_target =
+      ExternalReference::debug_after_break_target_address(masm->isolate());
+  __ mov(ip, Operand(after_break_target));
+  __ LoadP(ip, MemOperand(ip));
+  __ JumpToJSEntry(ip);
+}
+
+void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
+  // Load the function pointer off of our current stack frame.
+  __ LoadP(r3, MemOperand(fp, FrameDropperFrameConstants::kFunctionOffset));
+
+  // Pop return address and frame
+  __ LeaveFrame(StackFrame::INTERNAL);
+
+  ParameterCount dummy(0);
+  __ FloodFunctionIfStepping(r3, no_reg, dummy, dummy);
+
+  // Load context from the function.
+  __ LoadP(cp, FieldMemOperand(r3, JSFunction::kContextOffset));
+
+  // Clear new.target as a safety measure.
+  __ LoadRoot(r5, Heap::kUndefinedValueRootIndex);
+
+  // Get function code.
+  __ LoadP(ip, FieldMemOperand(r3, JSFunction::kSharedFunctionInfoOffset));
+  __ LoadP(ip, FieldMemOperand(ip, SharedFunctionInfo::kCodeOffset));
+  __ AddP(ip, Operand(Code::kHeaderSize - kHeapObjectTag));
+
+  // Re-run JSFunction, r3 is function, cp is context.
+  __ Jump(ip);
+}
+
+const bool LiveEdit::kFrameDropperSupported = true;
+
+#undef __
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_TARGET_ARCH_S390