diff --git a/dom/base/TimeoutHandler.cpp b/dom/base/TimeoutHandler.cpp
index 891e4c8f6a69..0e052966785e 100644
--- a/dom/base/TimeoutHandler.cpp
+++ b/dom/base/TimeoutHandler.cpp
@@ -29,6 +29,11 @@ void TimeoutHandler::GetLocation(const char** aFileName, uint32_t* aLineNo,
   *aColumn = mColumn;
 }
 
+void TimeoutHandler::GetDescription(nsACString& aOutString) {
+  aOutString.AppendPrintf("<generic handler> (%s:%d:%d)", mFileName.get(),
+                          mLineNo, mColumn);
+}
+
 NS_IMPL_CYCLE_COLLECTION_0(TimeoutHandler)
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(TimeoutHandler)
@@ -84,6 +89,19 @@ NS_INTERFACE_MAP_END_INHERITING(TimeoutHandler)
 NS_IMPL_ADDREF_INHERITED(ScriptTimeoutHandler, TimeoutHandler)
 NS_IMPL_RELEASE_INHERITED(ScriptTimeoutHandler, TimeoutHandler)
 
+void ScriptTimeoutHandler::GetDescription(nsACString& aOutString) {
+  if (mExpr.Length() > 15) {
+    aOutString.AppendPrintf(
+        "<string handler (truncated): \"%s...\"> (%s:%d:%d)",
+        NS_ConvertUTF16toUTF8(Substring(mExpr, 0, 13)).get(), mFileName.get(),
+        mLineNo, mColumn);
+  } else {
+    aOutString.AppendPrintf("<string handler: \"%s\"> (%s:%d:%d)",
+                            NS_ConvertUTF16toUTF8(mExpr).get(), mFileName.get(),
+                            mLineNo, mColumn);
+  }
+}
+
 //-----------------------------------------------------------------------------
 // CallbackTimeoutHandler
 //-----------------------------------------------------------------------------
@@ -167,5 +185,9 @@ bool CallbackTimeoutHandler::Call(const char* aExecutionReason) {
 
 void CallbackTimeoutHandler::MarkForCC() { mFunction->MarkForCC(); }
 
+void CallbackTimeoutHandler::GetDescription(nsACString& aOutString) {
+  mFunction->GetDescription(aOutString);
+}
+
 }  // namespace dom
 }  // namespace mozilla
diff --git a/dom/base/TimeoutHandler.h b/dom/base/TimeoutHandler.h
index c05bc616a26a..7bcd1914b1fd 100644
--- a/dom/base/TimeoutHandler.h
+++ b/dom/base/TimeoutHandler.h
@@ -34,6 +34,12 @@ class TimeoutHandler : public nsISupports {
   // nsITimeoutHandler and should not be freed by the caller.
   virtual void GetLocation(const char** aFileName, uint32_t* aLineNo,
                            uint32_t* aColumn);
+  // Append a UTF-8 string to aOutString that describes the callback function,
+  // for use in logging or profiler markers.
+  // The string contains the function name and its source location, if
+  // available, in the following format:
+  // "<functionName> (<sourceURL>:<lineNumber>:<columnNumber>)"
+  virtual void GetDescription(nsACString& aOutString);
   virtual void MarkForCC() {}
 
  protected:
@@ -65,6 +71,7 @@ class ScriptTimeoutHandler : public TimeoutHandler {
   MOZ_CAN_RUN_SCRIPT virtual bool Call(const char* /* unused */) override {
     return false;
   };
+  virtual void GetDescription(nsACString& aOutString) override;
 
  protected:
   virtual ~ScriptTimeoutHandler() {}
@@ -87,6 +94,7 @@ class CallbackTimeoutHandler final : public TimeoutHandler {
 
   MOZ_CAN_RUN_SCRIPT virtual bool Call(const char* aExecutionReason) override;
   virtual void MarkForCC() override;
+  virtual void GetDescription(nsACString& aOutString) override;
 
   void ReleaseJSObjects();