diff --git a/renderdoc/driver/shaders/spirv/spirv_debug.cpp b/renderdoc/driver/shaders/spirv/spirv_debug.cpp
index 381f11297..83219deaf 100644
--- a/renderdoc/driver/shaders/spirv/spirv_debug.cpp
+++ b/renderdoc/driver/shaders/spirv/spirv_debug.cpp
@@ -24,6 +24,7 @@
 
 #include "spirv_debug.h"
 #include <math.h>
+#include <time.h>
 #include "common/formatting.h"
 #include "spirv_op_helpers.h"
 
@@ -63,7 +64,7 @@ ThreadState::ThreadState(uint32_t workgroupIdx, Debugger &debug, const GlobalSta
 {
   workgroupIndex = workgroupIdx;
   nextInstruction = 0;
-  done = false;
+  helperInvocation = false;
 }
 
 ThreadState::~ThreadState()
@@ -75,7 +76,7 @@ ThreadState::~ThreadState()
 
 bool ThreadState::Finished() const
 {
-  return done || callstack.empty();
+  return helperInvocation || callstack.empty();
 }
 
 void ThreadState::FillCallstack(ShaderDebugState &state)
@@ -1809,6 +1810,46 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
       break;
     }
 
+    //////////////////////////////////////////////////////////////////////////////
+    //
+    // Misc opcodes
+    //
+    //////////////////////////////////////////////////////////////////////////////
+
+    case Op::ReadClockKHR:
+    {
+      const DataType &resultType = debugger.GetType(opdata.resultType);
+
+      ShaderVariable result;
+
+      result.type = resultType.scalar().Type();
+      result.rows = 1;
+      result.columns = RDCMAX(1U, resultType.vector().count);
+
+      result.value.u64v[0] = global.clock;
+
+      SetDst(state, opdata.result, result);
+      break;
+    }
+    case Op::IsHelperInvocationEXT:
+    {
+      ShaderVariable result;
+
+      result.type = VarType::UInt;
+      result.rows = 1;
+      result.columns = 1;
+
+      result.value.u.x = helperInvocation;
+
+      SetDst(state, opdata.result, result);
+      break;
+    }
+    case Op::DemoteToHelperInvocationEXT:
+    {
+      helperInvocation = true;
+      break;
+    }
+
     //////////////////////////////////////////////////////////////////////////////
     //
     // Function flow control opcodes
diff --git a/renderdoc/driver/shaders/spirv/spirv_debug.h b/renderdoc/driver/shaders/spirv/spirv_debug.h
index ea3b25195..6908c80ea 100644
--- a/renderdoc/driver/shaders/spirv/spirv_debug.h
+++ b/renderdoc/driver/shaders/spirv/spirv_debug.h
@@ -115,6 +115,8 @@ public:
   rdcarray<ShaderVariable> samplers;
 
   SparseIdMap<ExtInstDispatcher> extInsts;
+
+  uint64_t clock;
 };
 
 struct StackFrame
@@ -195,7 +197,7 @@ struct ThreadState
 
   // index in the pixel quad
   uint32_t workgroupIndex;
-  bool done;
+  bool helperInvocation;
 
   const ShaderVariable &GetSrc(Id id) const;
 
diff --git a/renderdoc/driver/shaders/spirv/spirv_debug_setup.cpp b/renderdoc/driver/shaders/spirv/spirv_debug_setup.cpp
index eb780fb18..9c10329c2 100644
--- a/renderdoc/driver/shaders/spirv/spirv_debug_setup.cpp
+++ b/renderdoc/driver/shaders/spirv/spirv_debug_setup.cpp
@@ -339,6 +339,8 @@ ShaderDebugTrace *Debugger::BeginDebug(DebugAPIWrapper *apiWrapper, const Shader
     }
   }
 
+  global.clock = uint64_t(time(NULL)) << 32;
+
   for(auto it = extSets.begin(); it != extSets.end(); it++)
   {
     Id id = it->first;
@@ -638,7 +640,7 @@ ShaderDebugTrace *Debugger::BeginDebug(DebugAPIWrapper *apiWrapper, const Shader
       lane.outputs = active.outputs;
       lane.ids = active.ids;
       // mark as inactive/helper lane
-      lane.done = true;
+      lane.helperInvocation = true;
     }
 
     // now that the globals are allocated and their storage won't move, we can take pointers to them
@@ -774,6 +776,8 @@ rdcarray<ShaderDebugState> Debugger::ContinueDebug()
   // do 100 in a chunk
   for(int cycleCounter = 0; cycleCounter < 100; cycleCounter++)
   {
+    global.clock++;
+
     if(active.Finished())
       break;