diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index 5229948e01..580d6bfba3 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -224,16 +224,23 @@ ProcessNameForCollectorLog()
 
 namespace xpc {
 
-// This handles JS Exceptions (via ExceptionStackOrNull), as well as DOM and XPC
-// Exceptions.
+// This handles JS Exceptions (via ExceptionStackOrNull), DOM and XPC
+// Exceptions, and arbitrary values that were associated with a stack by the
+// JS engine when they were thrown, as specified by exceptionStack.
 //
 // Note that the returned object is _not_ wrapped into the compartment of
 // exceptionValue.
 JSObject*
 FindExceptionStackForConsoleReport(nsPIDOMWindowInner* win,
-                                   JS::HandleValue exceptionValue)
+                                   JS::HandleValue exceptionValue,
+                                   JS::HandleObject exceptionStack)
 {
   if (!exceptionValue.isObject()) {
+    // Use the stack provided by the JS engine, if available. This will not be
+    // a wrapper.
+    if (exceptionStack) {
+      return exceptionStack;
+    }
     return nullptr;
   }
 
@@ -257,6 +264,10 @@ FindExceptionStackForConsoleReport(nsPIDOMWindowInner* win,
     // Not a DOM Exception, try XPC Exception.
     UNWRAP_OBJECT(Exception, exceptionObject, exception);
     if (!exception) {
+      // As above, use the stack provided by the JS engine, if available.
+      if (exceptionStack) {
+        return exceptionStack;
+      }
       return nullptr;
     }
   }
@@ -421,10 +432,12 @@ public:
   ScriptErrorEvent(nsPIDOMWindowInner* aWindow,
                    JS::RootingContext* aRootingCx,
                    xpc::ErrorReport* aReport,
-                   JS::Handle<JS::Value> aError)
+                   JS::Handle<JS::Value> aError,
+                   JS::Handle<JSObject*> aErrorStack)
     : mWindow(aWindow)
     , mReport(aReport)
     , mError(aRootingCx, aError)
+    , mErrorStack(aRootingCx, aErrorStack)
   {}
 
   NS_IMETHOD Run() override
@@ -471,7 +484,7 @@ public:
 
     if (status != nsEventStatus_eConsumeNoDefault) {
       JS::Rooted<JSObject*> stack(rootingCx,
-        xpc::FindExceptionStackForConsoleReport(win, mError));
+        xpc::FindExceptionStackForConsoleReport(win, mError, mErrorStack));
       mReport->LogToConsoleWithStack(stack);
     }
 
@@ -481,7 +494,8 @@ public:
 private:
   nsCOMPtr<nsPIDOMWindowInner>  mWindow;
   RefPtr<xpc::ErrorReport>      mReport;
-  JS::PersistentRootedValue       mError;
+  JS::PersistentRootedValue     mError;
+  JS::PersistentRootedObject    mErrorStack;
 
   static bool sHandlingScriptError;
 };
@@ -494,9 +508,10 @@ namespace xpc {
 
 void
 DispatchScriptErrorEvent(nsPIDOMWindowInner *win, JS::RootingContext* rootingCx,
-                         xpc::ErrorReport *xpcReport, JS::Handle<JS::Value> exception)
+                         xpc::ErrorReport *xpcReport, JS::Handle<JS::Value> exception,
+                         JS::Handle<JSObject*> exceptionStack)
 {
-  nsContentUtils::AddScriptRunner(new ScriptErrorEvent(win, rootingCx, xpcReport, exception));
+  nsContentUtils::AddScriptRunner(new ScriptErrorEvent(win, rootingCx, xpcReport, exception, exceptionStack));
 }
 
 } /* namespace xpc */
diff --git a/dom/script/ScriptSettings.cpp b/dom/script/ScriptSettings.cpp
index 514b5cf858..790394de65 100644
--- a/dom/script/ScriptSettings.cpp
+++ b/dom/script/ScriptSettings.cpp
@@ -577,8 +577,9 @@ AutoJSAPI::ReportException()
   }
   JSAutoCompartment ac(cx(), errorGlobal);
   JS::Rooted<JS::Value> exn(cx());
+  JS::Rooted<JSObject*> exnStack(cx());
   js::ErrorReport jsReport(cx());
-  if (StealException(&exn) &&
+  if (StealExceptionAndStack(&exn, &exnStack) &&
       jsReport.init(cx(), exn, js::ErrorReport::WithSideEffects)) {
     if (mIsMainThread) {
       RefPtr<xpc::ErrorReport> xpcReport = new xpc::ErrorReport();
@@ -595,10 +596,10 @@ AutoJSAPI::ReportException()
                       inner ? inner->WindowID() : 0);
       if (inner && jsReport.report()->errorNumber != JSMSG_OUT_OF_MEMORY) {
         JS::RootingContext* rcx = JS::RootingContext::get(cx());
-        DispatchScriptErrorEvent(inner, rcx, xpcReport, exn);
+        DispatchScriptErrorEvent(inner, rcx, xpcReport, exn, exnStack);
       } else {
         JS::Rooted<JSObject*> stack(cx(),
-          xpc::FindExceptionStackForConsoleReport(inner, exn));
+          xpc::FindExceptionStackForConsoleReport(inner, exn, exnStack));
         xpcReport->LogToConsoleWithStack(stack);
       }
     } else {
@@ -638,9 +639,16 @@ AutoJSAPI::PeekException(JS::MutableHandle<JS::Value> aVal)
 bool
 AutoJSAPI::StealException(JS::MutableHandle<JS::Value> aVal)
 {
+  JS::Rooted<JSObject*> stack(cx());
+  return StealExceptionAndStack(aVal, &stack);
+}
+
+bool AutoJSAPI::StealExceptionAndStack(JS::MutableHandle<JS::Value> aVal,
+                                       JS::MutableHandle<JSObject*> aStack) {
   if (!PeekException(aVal)) {
     return false;
   }
+  aStack.set(JS::GetPendingExceptionStack(cx()));
   JS_ClearPendingException(cx());
   return true;
 }
diff --git a/dom/script/ScriptSettings.h b/dom/script/ScriptSettings.h
index f6cfb6c3e4..f2e12f0be9 100644
--- a/dom/script/ScriptSettings.h
+++ b/dom/script/ScriptSettings.h
@@ -274,6 +274,12 @@ public:
   // into the current compartment.
   MOZ_MUST_USE bool StealException(JS::MutableHandle<JS::Value> aVal);
 
+  // As for StealException(), but put the saved frames for any stack trace
+  // associated with the point the exception was thrown into aStack.
+  // aVal will be in the current compartment, but aStack might not be.
+  MOZ_MUST_USE bool StealExceptionAndStack(JS::MutableHandle<JS::Value> aVal,
+                                           JS::MutableHandle<JSObject*> aStack);
+
   // Peek the current exception from the JS engine, without stealing it.
   // Callers must ensure that HasException() is true, and that cx() is in a
   // non-null compartment.
diff --git a/js/src/jit/VMFunctions.cpp b/js/src/jit/VMFunctions.cpp
index fbe6977bf9..01a22482eb 100644
--- a/js/src/jit/VMFunctions.cpp
+++ b/js/src/jit/VMFunctions.cpp
@@ -941,7 +941,7 @@ HandleDebugTrap(JSContext* cx, BaselineFrame* frame, uint8_t* retAddr, bool* mus
         return jit::DebugEpilogue(cx, frame, pc, true);
 
       case JSTRAP_THROW:
-        cx->setPendingException(rval);
+        cx->setPendingExceptionAndCaptureStack(rval);
         return false;
 
       default:
diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index 7d32948a27..0d23c96cb4 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -6219,12 +6219,16 @@ JS_GetPendingException(JSContext* cx, MutableHandleValue vp)
 }
 
 JS_PUBLIC_API(void)
-JS_SetPendingException(JSContext* cx, HandleValue value)
+JS_SetPendingException(JSContext* cx, HandleValue value, JS::ExceptionStackBehavior behavior)
 {
     AssertHeapIsIdle(cx);
     CHECK_REQUEST(cx);
     releaseAssertSameCompartment(cx, value);
-    cx->setPendingException(value);
+    if (behavior == JS::ExceptionStackBehavior::Capture) {
+        cx->setPendingExceptionAndCaptureStack(value);
+    } else {
+        cx->setPendingException(value, nullptr);
+    }
 }
 
 JS_PUBLIC_API(void)
@@ -6234,12 +6238,20 @@ JS_ClearPendingException(JSContext* cx)
     cx->clearPendingException();
 }
 
+JS_PUBLIC_API(JSObject*)
+JS::GetPendingExceptionStack(JSContext* cx)
+{
+  AssertHeapIsIdle(cx);
+  return cx->getPendingExceptionStack();
+}
+
 JS::AutoSaveExceptionState::AutoSaveExceptionState(JSContext* cx)
   : context(cx),
     wasPropagatingForcedReturn(cx->propagatingForcedReturn_),
     wasOverRecursed(cx->overRecursed_),
     wasThrowing(cx->throwing),
-    exceptionValue(cx)
+    exceptionValue(cx),
+    exceptionStack(cx)
 {
     AssertHeapIsIdle(cx);
     CHECK_REQUEST(cx);
@@ -6249,10 +6261,21 @@ JS::AutoSaveExceptionState::AutoSaveExceptionState(JSContext* cx)
         cx->overRecursed_ = false;
     if (wasThrowing) {
         exceptionValue = cx->unwrappedException_;
+        exceptionStack = cx->unwrappedExceptionStack_;
         cx->clearPendingException();
     }
 }
 
+void
+JS::AutoSaveExceptionState::drop()
+{
+  wasPropagatingForcedReturn = false;
+  wasOverRecursed = false;
+  wasThrowing = false;
+  exceptionValue.setUndefined();
+  exceptionStack = nullptr;
+}
+
 void
 JS::AutoSaveExceptionState::restore()
 {
@@ -6260,6 +6283,9 @@ JS::AutoSaveExceptionState::restore()
     context->overRecursed_ = wasOverRecursed;
     context->throwing = wasThrowing;
     context->unwrappedException_ = exceptionValue;
+    if (exceptionStack) {
+      context->unwrappedExceptionStack_ = &exceptionStack->as<SavedFrame>();
+    }
     drop();
 }
 
@@ -6272,6 +6298,9 @@ JS::AutoSaveExceptionState::~AutoSaveExceptionState()
             context->overRecursed_ = wasOverRecursed;
             context->throwing = true;
             context->unwrappedException_ = exceptionValue;
+            if (exceptionStack) {
+                context->unwrappedExceptionStack_ = &exceptionStack->as<SavedFrame>();
+            }
         }
     }
 }
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 938fcb2a33..6002d86ad5 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -5762,8 +5762,22 @@ JS_IsExceptionPending(JSContext* cx);
 extern JS_PUBLIC_API(bool)
 JS_GetPendingException(JSContext* cx, JS::MutableHandleValue vp);
 
+namespace JS {
+
+enum class ExceptionStackBehavior: bool {
+  // Do not capture any stack.
+  DoNotCapture,
+
+  // Capture the current JS stack when setting the exception. It may be
+  // retrieved by JS::GetPendingExceptionStack.
+  Capture
+};
+
+} // namespace JS
+
 extern JS_PUBLIC_API(void)
-JS_SetPendingException(JSContext* cx, JS::HandleValue v);
+JS_SetPendingException(JSContext* cx, JS::HandleValue v,
+                       JS::ExceptionStackBehavior behavior = JS::ExceptionStackBehavior::Capture);
 
 extern JS_PUBLIC_API(void)
 JS_ClearPendingException(JSContext* cx);
@@ -5790,6 +5804,7 @@ class JS_PUBLIC_API(AutoSaveExceptionState)
     bool wasOverRecursed;
     bool wasThrowing;
     RootedValue exceptionValue;
+    RootedObject exceptionStack;
 
   public:
     /*
@@ -5808,12 +5823,7 @@ class JS_PUBLIC_API(AutoSaveExceptionState)
      * Discard any stored exception state.
      * If this is called, the destructor is a no-op.
      */
-    void drop() {
-        wasPropagatingForcedReturn = false;
-        wasOverRecursed = false;
-        wasThrowing = false;
-        exceptionValue.setUndefined();
-    }
+    void drop();
 
     /*
      * Replace cx's exception state with the stored exception state. Then
@@ -5823,6 +5833,18 @@ class JS_PUBLIC_API(AutoSaveExceptionState)
     void restore();
 };
 
+/**
+ * Get the SavedFrame stack object captured when the pending exception was set
+ * on the JSContext. This fuzzily correlates with a `throw` statement in JS,
+ * although arbitrary JSAPI consumers or VM code may also set pending exceptions
+ * via `JS_SetPendingException`.
+ *
+ * This is not the same stack as `e.stack` when `e` is an `Error` object. (That
+ * would be JS::ExceptionStackOrNull).
+ */
+MOZ_MUST_USE JS_PUBLIC_API(JSObject*)
+GetPendingExceptionStack(JSContext* cx);
+
 } /* namespace JS */
 
 /* Deprecated API. Use AutoSaveExceptionState instead. */
diff --git a/js/src/jscntxt.cpp b/js/src/jscntxt.cpp
index baab36183a..c780b7feba 100644
--- a/js/src/jscntxt.cpp
+++ b/js/src/jscntxt.cpp
@@ -241,7 +241,8 @@ js::ReportOutOfMemory(ExclusiveContext* cxArg)
     if (JS::OutOfMemoryCallback oomCallback = cx->runtime()->oomCallback)
         oomCallback(cx, cx->runtime()->oomCallbackData);
 
-    cx->setPendingException(StringValue(cx->names().outOfMemory));
+    RootedValue oomMessage(cx, StringValue(cx->names().outOfMemory));
+    cx->setPendingException(oomMessage, nullptr);
 }
 
 void
@@ -1013,6 +1014,7 @@ JSContext::JSContext(JSRuntime* parentRuntime)
     JSRuntime(parentRuntime),
     throwing(false),
     unwrappedException_(this),
+    unwrappedExceptionStack_(this),
     overRecursed_(false),
     propagatingForcedReturn_(false),
     liveVolatileJitFrameIterators_(nullptr),
@@ -1038,6 +1040,24 @@ JSContext::~JSContext()
     MOZ_ASSERT(!resolvingList);
 }
 
+
+void
+JSContext::setPendingExceptionAndCaptureStack(HandleValue value)
+{
+    static const size_t MAX_REPORTED_STACK_DEPTH = 1u << 7;
+
+    RootedObject stack(this);
+    if (!CaptureCurrentStack(this, &stack, JS::StackCapture(JS::MaxFrames(MAX_REPORTED_STACK_DEPTH)))) {
+        clearPendingException();
+    }
+
+    RootedSavedFrame nstack(this);
+    if (stack) {
+        nstack = &stack->as<SavedFrame>();
+    }
+    setPendingException(value, nstack);
+}
+
 bool
 JSContext::getPendingException(MutableHandleValue rval)
 {
@@ -1045,16 +1065,23 @@ JSContext::getPendingException(MutableHandleValue rval)
     rval.set(unwrappedException_);
     if (IsAtomsCompartment(compartment()))
         return true;
+    RootedSavedFrame stack(this, unwrappedExceptionStack_);
     bool wasOverRecursed = overRecursed_;
     clearPendingException();
     if (!compartment()->wrap(this, rval))
         return false;
     assertSameCompartment(this, rval);
-    setPendingException(rval);
+    setPendingException(rval, stack);
     overRecursed_ = wasOverRecursed;
     return true;
 }
 
+SavedFrame*
+JSContext::getPendingExceptionStack()
+{
+    return unwrappedExceptionStack_;
+}
+
 bool
 JSContext::isThrowingOutOfMemory()
 {
diff --git a/js/src/jscntxt.h b/js/src/jscntxt.h
index 935e6c59e5..93106d681e 100644
--- a/js/src/jscntxt.h
+++ b/js/src/jscntxt.h
@@ -369,6 +369,7 @@ struct JSContext : public js::ExclusiveContext,
     /* Exception state -- the exception member is a GC root by definition. */
     bool                throwing;            /* is there a pending exception? */
     JS::PersistentRooted<JS::Value> unwrappedException_; /* most-recently-thrown exception */
+    JS::PersistentRooted<js::SavedFrame*> unwrappedExceptionStack_; /* stack when the exception was thrown */
 
     // True if the exception currently being thrown is by result of
     // ReportOverRecursed. See Debugger::slowPathOnExceptionUnwind.
@@ -495,17 +496,21 @@ struct JSContext : public js::ExclusiveContext,
 
     MOZ_MUST_USE
     bool getPendingException(JS::MutableHandleValue rval);
+    
+    js::SavedFrame* getPendingExceptionStack();
 
     bool isThrowingOutOfMemory();
     bool isThrowingDebuggeeWouldRun();
     bool isClosingGenerator();
 
-    void setPendingException(const js::Value& v);
+    void setPendingException(JS::HandleValue v, js::HandleSavedFrame stack);
+    void setPendingExceptionAndCaptureStack(JS::HandleValue v);
 
     void clearPendingException() {
         throwing = false;
         overRecursed_ = false;
         unwrappedException_.setUndefined();
+        unwrappedExceptionStack_ = nullptr;
     }
 
     bool isThrowingOverRecursed() const { return throwing && overRecursed_; }
diff --git a/js/src/jscntxtinlines.h b/js/src/jscntxtinlines.h
index e08541e8da..c89ef86ec2 100644
--- a/js/src/jscntxtinlines.h
+++ b/js/src/jscntxtinlines.h
@@ -368,12 +368,13 @@ ExclusiveContext::typeLifoAlloc()
 }  /* namespace js */
 
 inline void
-JSContext::setPendingException(const js::Value& v)
+JSContext::setPendingException(JS::HandleValue v, js::HandleSavedFrame stack)
 {
     // overRecursed_ is set after the fact by ReportOverRecursed.
     this->overRecursed_ = false;
     this->throwing = true;
     this->unwrappedException_ = v;
+    this->unwrappedExceptionStack_ = stack;
     // We don't use assertSameCompartment here to allow
     // js::SetPendingExceptionCrossContext to work.
     MOZ_ASSERT_IF(v.isObject(), v.toObject().compartment() == compartment());
diff --git a/js/src/jsexn.cpp b/js/src/jsexn.cpp
index 7f87c312d3..2eb8e7d105 100644
--- a/js/src/jsexn.cpp
+++ b/js/src/jsexn.cpp
@@ -361,13 +361,13 @@ struct SuppressErrorsGuard
     }
 };
 
-// Cut off the stack if it gets too deep (most commonly for infinite recursion
-// errors).
-static const size_t MAX_REPORTED_STACK_DEPTH = 1u << 7;
-
 static bool
 CaptureStack(JSContext* cx, MutableHandleObject stack)
 {
+    // Cut off the stack if it gets too deep (most commonly for infinite recursion
+    // errors).
+    static const size_t MAX_REPORTED_STACK_DEPTH = 1u << 7;
+
     return CaptureCurrentStack(cx, stack,
                                JS::StackCapture(JS::MaxFrames(MAX_REPORTED_STACK_DEPTH)));
 }
@@ -699,7 +699,12 @@ js::ErrorToException(JSContext* cx, JSErrorReport* reportp,
         return;
 
     // Throw it.
-    cx->setPendingException(ObjectValue(*errObject));
+    RootedValue errValue(cx, ObjectValue(*errObject));
+    RootedSavedFrame nstack(cx);
+    if (stack) {
+      nstack = &stack->as<SavedFrame>();
+    }
+    cx->setPendingException(errValue, nstack);
 
     // Flag the error report passed in to indicate an exception was raised.
     reportp->flags |= JSREPORT_EXCEPTION;
diff --git a/js/src/jsiter.cpp b/js/src/jsiter.cpp
index 96285c1665..858e10a326 100644
--- a/js/src/jsiter.cpp
+++ b/js/src/jsiter.cpp
@@ -971,8 +971,10 @@ js::ThrowStopIteration(JSContext* cx)
     // StopIteration isn't a constructor, but it's stored in GlobalObject
     // as one, out of laziness. Hence the GetBuiltinConstructor call here.
     RootedObject ctor(cx);
-    if (GetBuiltinConstructor(cx, JSProto_StopIteration, &ctor))
-        cx->setPendingException(ObjectValue(*ctor));
+    if (GetBuiltinConstructor(cx, JSProto_StopIteration, &ctor)) {
+        RootedValue ctorval(cx, ObjectValue(*ctor));
+        cx->setPendingExceptionAndCaptureStack(ctorval);
+    }
     return false;
 }
 
@@ -1261,12 +1263,13 @@ js::UnwindIteratorForException(JSContext* cx, HandleObject obj)
 {
     RootedValue v(cx);
     bool getOk = cx->getPendingException(&v);
+    RootedSavedFrame stack(cx, cx->getPendingExceptionStack());
     cx->clearPendingException();
     if (!CloseIterator(cx, obj))
         return false;
     if (!getOk)
         return false;
-    cx->setPendingException(v);
+    cx->setPendingException(v, stack);
     return true;
 }
 
diff --git a/js/src/proxy/Wrapper.cpp b/js/src/proxy/Wrapper.cpp
index 36cb1317f7..314409bba1 100644
--- a/js/src/proxy/Wrapper.cpp
+++ b/js/src/proxy/Wrapper.cpp
@@ -408,12 +408,15 @@ ErrorCopier::~ErrorCopier()
     {
         RootedValue exc(cx);
         if (cx->getPendingException(&exc) && exc.isObject() && exc.toObject().is<ErrorObject>()) {
+            RootedSavedFrame stack(cx, cx->getPendingExceptionStack());
             cx->clearPendingException();
             ac.reset();
             Rooted<ErrorObject*> errObj(cx, &exc.toObject().as<ErrorObject>());
             JSObject* copyobj = CopyErrorObject(cx, errObj);
-            if (copyobj)
-                cx->setPendingException(ObjectValue(*copyobj));
+            if (copyobj) {
+                RootedValue rootedCopy(cx, ObjectValue(*copyobj));
+                cx->setPendingException(rootedCopy, stack);
+            }
         }
     }
 }
diff --git a/js/src/vm/Debugger.cpp b/js/src/vm/Debugger.cpp
index f665dcef9b..f844d1d482 100644
--- a/js/src/vm/Debugger.cpp
+++ b/js/src/vm/Debugger.cpp
@@ -848,7 +848,7 @@ Debugger::slowPathOnEnterFrame(JSContext* cx, AbstractFramePtr frame)
         break;
 
       case JSTRAP_THROW:
-        cx->setPendingException(rval);
+        cx->setPendingExceptionAndCaptureStack(rval);
         break;
 
       case JSTRAP_ERROR:
@@ -960,7 +960,7 @@ Debugger::slowPathOnLeaveFrame(JSContext* cx, AbstractFramePtr frame, jsbytecode
         return true;
 
       case JSTRAP_THROW:
-        cx->setPendingException(value);
+        cx->setPendingExceptionAndCaptureStack(value);
         return false;
 
       case JSTRAP_ERROR:
@@ -993,7 +993,7 @@ Debugger::slowPathOnDebuggerStatement(JSContext* cx, AbstractFramePtr frame)
         break;
 
       case JSTRAP_THROW:
-        cx->setPendingException(rval);
+        cx->setPendingExceptionAndCaptureStack(rval);
         break;
 
       default:
@@ -1028,7 +1028,7 @@ Debugger::slowPathOnExceptionUnwind(JSContext* cx, AbstractFramePtr frame)
         break;
 
       case JSTRAP_THROW:
-        cx->setPendingException(rval);
+        cx->setPendingExceptionAndCaptureStack(rval);
         break;
 
       case JSTRAP_ERROR:
@@ -1321,7 +1321,7 @@ public:
 
     bool operator()(JSContext* cx) override
     {
-        cx->setPendingException(exn_);
+        cx->setPendingExceptionAndCaptureStack(exn_);
         return false;
     }
 
@@ -1753,6 +1753,7 @@ Debugger::fireExceptionUnwind(JSContext* cx, MutableHandleValue vp)
     MOZ_ASSERT(hook->isCallable());
 
     RootedValue exc(cx);
+    RootedSavedFrame stack(cx, cx->getPendingExceptionStack());
     if (!cx->getPendingException(&exc))
         return JSTRAP_ERROR;
     cx->clearPendingException();
@@ -1772,7 +1773,7 @@ Debugger::fireExceptionUnwind(JSContext* cx, MutableHandleValue vp)
     bool ok = js::Call(cx, fval, object, scriptFrame, wrappedExc, &rv);
     JSTrapStatus st = processHandlerResult(ac, ok, rv, iter.abstractFramePtr(), iter.pc(), vp);
     if (st == JSTRAP_CONTINUE)
-        cx->setPendingException(exc);
+        cx->setPendingException(exc, stack);
     return st;
 }
 
@@ -2005,13 +2006,7 @@ Debugger::onSingleStep(JSContext* cx, MutableHandleValue vp)
      * onStep handlers mess with that (other than by returning a resumption
      * value).
      */
-    RootedValue exception(cx, UndefinedValue());
-    bool exceptionPending = cx->isExceptionPending();
-    if (exceptionPending) {
-        if (!cx->getPendingException(&exception))
-            return JSTRAP_ERROR;
-        cx->clearPendingException();
-    }
+    JS::AutoSaveExceptionState savedExc(cx);
 
     /*
      * Build list of Debugger.Frame instances referring to this frame with
@@ -2070,13 +2065,13 @@ Debugger::onSingleStep(JSContext* cx, MutableHandleValue vp)
         bool ok = js::Call(cx, fval, frame, &rval);
         JSTrapStatus st = dbg->processHandlerResult(ac, ok, rval, iter.abstractFramePtr(),
                                                     iter.pc(), vp);
-        if (st != JSTRAP_CONTINUE)
+        if (st != JSTRAP_CONTINUE) {
+            savedExc.drop();
             return st;
+        }
     }
 
     vp.setUndefined();
-    if (exceptionPending)
-        cx->setPendingException(exception);
     return JSTRAP_CONTINUE;
 }
 
diff --git a/js/src/vm/ForOfIterator.cpp b/js/src/vm/ForOfIterator.cpp
index d616792697..abf27d0aee 100644
--- a/js/src/vm/ForOfIterator.cpp
+++ b/js/src/vm/ForOfIterator.cpp
@@ -158,9 +158,12 @@ ForOfIterator::closeThrow()
     MOZ_ASSERT(iterator);
 
     RootedValue completionException(cx_);
+    RootedSavedFrame completionExceptionStack(cx_);
     if (cx_->isExceptionPending()) {
-        if (!GetAndClearException(cx_, &completionException))
+        if (!GetAndClearExceptionAndStack(cx_, &completionException, &completionExceptionStack)) {
             completionException.setUndefined();
+            completionExceptionStack = nullptr;
+        }
     }
 
     // Steps 1-2 (implicit)
@@ -172,7 +175,7 @@ ForOfIterator::closeThrow()
 
     // Step 4.
     if (returnVal.isUndefined()) {
-        cx_->setPendingException(completionException);
+        cx_->setPendingException(completionException, completionExceptionStack);
         return;
     }
 
@@ -195,7 +198,7 @@ ForOfIterator::closeThrow()
     }
 
     // Step 6.
-    cx_->setPendingException(completionException);
+    cx_->setPendingException(completionException, completionExceptionStack);
 
     // Steps 7-9 (skipped).
     return;
diff --git a/js/src/vm/GeneratorObject.cpp b/js/src/vm/GeneratorObject.cpp
index 9265a1b628..df2869c89c 100644
--- a/js/src/vm/GeneratorObject.cpp
+++ b/js/src/vm/GeneratorObject.cpp
@@ -131,7 +131,7 @@ js::GeneratorThrowOrClose(JSContext* cx, AbstractFramePtr frame, Handle<Generato
                           HandleValue arg, uint32_t resumeKind)
 {
     if (resumeKind == GeneratorObject::THROW) {
-        cx->setPendingException(arg);
+        cx->setPendingExceptionAndCaptureStack(arg);
         genObj->setRunning();
     } else {
         MOZ_ASSERT(resumeKind == GeneratorObject::CLOSE);
@@ -143,7 +143,8 @@ js::GeneratorThrowOrClose(JSContext* cx, AbstractFramePtr frame, Handle<Generato
             MOZ_ASSERT(arg.isUndefined());
         }
 
-        cx->setPendingException(MagicValue(JS_GENERATOR_CLOSING));
+        RootedValue closing(cx, MagicValue(JS_GENERATOR_CLOSING));
+        cx->setPendingException(closing, nullptr);
         genObj->setClosing();
     }
     return false;
diff --git a/js/src/vm/Interpreter.cpp b/js/src/vm/Interpreter.cpp
index cf58e2d608..b95e533b6e 100644
--- a/js/src/vm/Interpreter.cpp
+++ b/js/src/vm/Interpreter.cpp
@@ -1883,7 +1883,7 @@ CASE(EnableInterruptsPseudoOpcode)
                     goto error;
                 goto successful_return_continuation;
               case JSTRAP_THROW:
-                cx->setPendingException(rval);
+                cx->setPendingExceptionAndCaptureStack(rval);
                 goto error;
               default:;
             }
@@ -1905,7 +1905,7 @@ CASE(EnableInterruptsPseudoOpcode)
                     goto error;
                 goto successful_return_continuation;
               case JSTRAP_THROW:
-                cx->setPendingException(rval);
+                cx->setPendingExceptionAndCaptureStack(rval);
                 goto error;
               default:
                 break;
@@ -3825,7 +3825,8 @@ CASE(JSOP_RETSUB)
          * be necessary, but it seems clearer.  And it points out a FIXME:
          * 350509, due to Igor Bukanov.
          */
-        cx->setPendingException(rval);
+        ReservedRooted<Value> v(&rootValue0, rval);
+        cx->setPendingExceptionAndCaptureStack(v);
         goto error;
     }
     MOZ_ASSERT(rval.isInt32());
@@ -4331,7 +4332,7 @@ bool
 js::Throw(JSContext* cx, HandleValue v)
 {
     MOZ_ASSERT(!cx->isExceptionPending());
-    cx->setPendingException(v);
+    cx->setPendingExceptionAndCaptureStack(v);
     return false;
 }
 
@@ -4342,7 +4343,7 @@ js::ThrowingOperation(JSContext* cx, HandleValue v)
     // execution instead of calling the (JIT) exception handler.
 
     MOZ_ASSERT(!cx->isExceptionPending());
-    cx->setPendingException(v);
+    cx->setPendingExceptionAndCaptureStack(v);
     return true;
 }
 
@@ -4548,16 +4549,25 @@ js::ThrowMsgOperation(JSContext* cx, const unsigned errorNum)
 }
 
 bool
-js::GetAndClearException(JSContext* cx, MutableHandleValue res)
+js::GetAndClearExceptionAndStack(JSContext* cx, MutableHandleValue res,
+                                 MutableHandleSavedFrame stack)
 {
     if (!cx->getPendingException(res))
         return false;
+    stack.set(cx->getPendingExceptionStack());
     cx->clearPendingException();
 
     // Allow interrupting deeply nested exception handling.
     return CheckForInterrupt(cx);
 }
 
+bool
+js::GetAndClearException(JSContext* cx, MutableHandleValue res)
+{
+    RootedSavedFrame stack(cx);
+    return GetAndClearExceptionAndStack(cx, res, &stack);
+}
+
 template <bool strict>
 bool
 js::DeletePropertyJit(JSContext* cx, HandleValue v, HandlePropertyName name, bool* bp)
diff --git a/js/src/vm/Interpreter.h b/js/src/vm/Interpreter.h
index 6a908e115b..df9368e71c 100644
--- a/js/src/vm/Interpreter.h
+++ b/js/src/vm/Interpreter.h
@@ -489,6 +489,9 @@ ThrowMsgOperation(JSContext* cx, const unsigned errorNum);
 bool
 GetAndClearException(JSContext* cx, MutableHandleValue res);
 
+bool
+GetAndClearExceptionAndStack(JSContext* cx, MutableHandleValue res, MutableHandleSavedFrame stack);
+
 bool
 DeleteNameOperation(JSContext* cx, HandlePropertyName name, HandleObject scopeObj,
                     MutableHandleValue res);
diff --git a/js/src/vm/Runtime.cpp b/js/src/vm/Runtime.cpp
index 251c8258cf..a12255c636 100644
--- a/js/src/vm/Runtime.cpp
+++ b/js/src/vm/Runtime.cpp
@@ -548,7 +548,7 @@ InvokeInterruptCallback(JSContext* cx)
                     Debugger::propagateForcedReturn(cx, iter.abstractFramePtr(), rval);
                     return false;
                   case JSTRAP_THROW:
-                    cx->setPendingException(rval);
+                    cx->setPendingExceptionAndCaptureStack(rval);
                     return false;
                   default:;
                 }
diff --git a/js/src/wasm/WasmJS.cpp b/js/src/wasm/WasmJS.cpp
index fb292ac941..0479bda59f 100644
--- a/js/src/wasm/WasmJS.cpp
+++ b/js/src/wasm/WasmJS.cpp
@@ -1729,7 +1729,8 @@ RejectWithPendingException(JSContext* cx, Handle<PromiseObject*> promise)
         return false;
 
     RootedValue rejectionValue(cx);
-    if (!GetAndClearException(cx, &rejectionValue))
+    RootedSavedFrame stack(cx);
+    if (!GetAndClearExceptionAndStack(cx, &rejectionValue, &stack))
         return false;
 
     return PromiseObject::reject(cx, promise, rejectionValue);
diff --git a/js/xpconnect/src/XPCComponents.cpp b/js/xpconnect/src/XPCComponents.cpp
index 594753d64f..70103dfd17 100644
--- a/js/xpconnect/src/XPCComponents.cpp
+++ b/js/xpconnect/src/XPCComponents.cpp
@@ -2310,7 +2310,7 @@ nsXPCComponents_Utils::ReportError(HandleValue error, JSContext* cx)
 
     if (errorObj) {
         JS::RootedObject stackVal(cx,
-          FindExceptionStackForConsoleReport(win, error));
+          FindExceptionStackForConsoleReport(win, error, nullptr));
         if (stackVal) {
             scripterr = new nsScriptErrorWithStack(stackVal);
         }
diff --git a/js/xpconnect/src/xpcpublic.h b/js/xpconnect/src/xpcpublic.h
index 56468f0edd..5351be979b 100644
--- a/js/xpconnect/src/xpcpublic.h
+++ b/js/xpconnect/src/xpcpublic.h
@@ -590,11 +590,13 @@ class ErrorReport : public ErrorBase {
 
 void
 DispatchScriptErrorEvent(nsPIDOMWindowInner* win, JS::RootingContext* rootingCx,
-                         xpc::ErrorReport* xpcReport, JS::Handle<JS::Value> exception);
+                         xpc::ErrorReport* xpcReport, JS::Handle<JS::Value> exception,
+                         JS::Handle<JSObject*> exceptionStack);
 
 // Get a stack of the sort that can be passed to
 // xpc::ErrorReport::LogToConsoleWithStack from the given exception value.  Can
-// return null if the exception value doesn't have an associated stack.  The
+// be nullptr if the exception value doesn't have an associated stack, and if
+// there is no stack supplied by the JS engine in exceptionStack.  The
 // returned stack, if any, may also not be in the same compartment as
 // exceptionValue.
 //
@@ -605,7 +607,8 @@ DispatchScriptErrorEvent(nsPIDOMWindowInner* win, JS::RootingContext* rootingCx,
 // the stack in the console message keeping the window alive.
 JSObject*
 FindExceptionStackForConsoleReport(nsPIDOMWindowInner* win,
-                                   JS::HandleValue exceptionValue);
+                                   JS::HandleValue exceptionValue,
+                                   JS::HandleObject exceptionStack);
 
 // Return a name for the compartment.
 // This function makes reasonable efforts to make this name both mostly human-readable