diff --git a/qrenderdoc/Code/QRDUtils.cpp b/qrenderdoc/Code/QRDUtils.cpp
index 3681401f4..f7e584898 100644
--- a/qrenderdoc/Code/QRDUtils.cpp
+++ b/qrenderdoc/Code/QRDUtils.cpp
@@ -1953,6 +1953,7 @@ public:
     setLabel(&m_Label);
   }
 
+  void enableCancel() { setCancelButtonText(tr("Cancel")); }
   void setPercentage(float percent) { setValue(int(maxProgress * percent)); }
   void setInfinite(bool infinite)
   {
@@ -2299,13 +2300,16 @@ QStringList ParseArgsList(const QString &args)
 }
 
 void ShowProgressDialog(QWidget *window, const QString &labelText, ProgressFinishedMethod finished,
-                        ProgressUpdateMethod update)
+                        ProgressUpdateMethod update, ProgressCancelMethod cancel)
 {
   if(finished())
     return;
 
   RDProgressDialog dialog(labelText, window);
 
+  if(cancel)
+    dialog.enableCancel();
+
   // if we don't have an update function, set the progress display to be 'infinite spinner'
   dialog.setInfinite(!update);
 
@@ -2338,6 +2342,9 @@ void ShowProgressDialog(QWidget *window, const QString &labelText, ProgressFinis
   // to clean itself up
   tickerSemaphore.tryAcquire();
   progressTickerThread.wait();
+
+  if(cancel && dialog.wasCanceled())
+    cancel();
 }
 
 void UpdateTransferProgress(qint64 xfer, qint64 total, QElapsedTimer *timer,
diff --git a/qrenderdoc/Code/QRDUtils.h b/qrenderdoc/Code/QRDUtils.h
index 42b54ee76..f512f9021 100644
--- a/qrenderdoc/Code/QRDUtils.h
+++ b/qrenderdoc/Code/QRDUtils.h
@@ -666,6 +666,7 @@ class QElapsedTimer;
 
 typedef std::function<float()> ProgressUpdateMethod;
 typedef std::function<bool()> ProgressFinishedMethod;
+typedef std::function<void()> ProgressCancelMethod;
 
 QStringList ParseArgsList(const QString &args);
 bool IsRunningAsAdmin();
@@ -676,7 +677,8 @@ bool RunProcessAsAdmin(const QString &fullExecutablePath, const QStringList &par
 void RevealFilenameInExternalFileBrowser(const QString &filePath);
 
 void ShowProgressDialog(QWidget *window, const QString &labelText, ProgressFinishedMethod finished,
-                        ProgressUpdateMethod update = ProgressUpdateMethod());
+                        ProgressUpdateMethod update = ProgressUpdateMethod(),
+                        ProgressCancelMethod cancel = ProgressCancelMethod());
 
 void UpdateTransferProgress(qint64 xfer, qint64 total, QElapsedTimer *timer,
                             QProgressBar *progressBar, QLabel *progressLabel, QString progressText);
diff --git a/qrenderdoc/Windows/ShaderViewer.cpp b/qrenderdoc/Windows/ShaderViewer.cpp
index 9c29af146..9bb3ee32b 100644
--- a/qrenderdoc/Windows/ShaderViewer.cpp
+++ b/qrenderdoc/Windows/ShaderViewer.cpp
@@ -663,19 +663,43 @@ void ShaderViewer::debugShader(const ShaderBindpointMapping *bind, const ShaderR
 
     cacheResources();
 
-    m_Ctx.Replay().AsyncInvoke([this](IReplayController *r) {
+    m_BackgroundRunning.release();
+
+    QPointer<ShaderViewer> me(this);
+
+    m_Ctx.Replay().AsyncInvoke([this, me](IReplayController *r) {
+      if(!me)
+        return;
+
       rdcarray<ShaderDebugState> states = r->ContinueDebug(m_Trace->debugger);
 
       bool finished = false;
       do
       {
+        if(!me)
+          return;
+
         rdcarray<ShaderDebugState> nextStates = r->ContinueDebug(m_Trace->debugger);
+
+        QThread::msleep(5000);
+
+        if(!me)
+          return;
+
         states.append(nextStates);
         finished = nextStates.empty();
-      } while(!finished);
+      } while(!finished && m_BackgroundRunning.available() == 1);
+
+      if(!me || m_BackgroundRunning.available() != 1)
+        return;
+
+      m_BackgroundRunning.tryAcquire(1);
 
       r->SetFrameEvent(m_Ctx.CurEvent(), true);
 
+      if(!me)
+        return;
+
       GUIInvoke::call(this, [this, states]() {
         m_States = states;
 
@@ -708,6 +732,18 @@ void ShaderViewer::debugShader(const ShaderBindpointMapping *bind, const ShaderR
       });
     });
 
+    GUIInvoke::defer(this, [this, debugContext]() {
+      // wait a short while before displaying the progress dialog (which won't show if we're already
+      // done by the time we reach it)
+      for(int i = 0; m_BackgroundRunning.available() == 1 && i < 100; i++)
+        QThread::msleep(5);
+
+      ShowProgressDialog(this, tr("Debugging %1").arg(debugContext),
+                         [this]() { return m_BackgroundRunning.available() == 0; }, NULL,
+                         [this]() { m_BackgroundRunning.acquire(); });
+
+    });
+
     m_CurrentStateIdx = 0;
 
     QObject::connect(ui->watch, &RDTableWidget::keyPress, this, &ShaderViewer::watch_keyPress);
diff --git a/qrenderdoc/Windows/ShaderViewer.h b/qrenderdoc/Windows/ShaderViewer.h
index f0e2a1930..c3710f117 100644
--- a/qrenderdoc/Windows/ShaderViewer.h
+++ b/qrenderdoc/Windows/ShaderViewer.h
@@ -25,6 +25,7 @@
 #pragma once
 
 #include <QFrame>
+#include <QSemaphore>
 #include "Code/Interface/QRDInterface.h"
 
 namespace Ui
@@ -254,6 +255,8 @@ private:
   size_t m_CurrentStateIdx = 0;
   rdcarray<ShaderVariable> m_Variables;
 
+  QSemaphore m_BackgroundRunning;
+
   rdcarray<AccessedResourceData> m_AccessedResources;
   AccessedResourceView m_AccessedResourceView = AccessedResourceView::SortByResource;