diff --git a/layout/style/nsCSSRuleProcessor.cpp b/layout/style/nsCSSRuleProcessor.cpp
index 5e419df06932..cf8ba07ea20d 100644
--- a/layout/style/nsCSSRuleProcessor.cpp
+++ b/layout/style/nsCSSRuleProcessor.cpp
@@ -810,10 +810,30 @@ RuleProcessorData::~RuleProcessorData()
 {
   MOZ_COUNT_DTOR(RuleProcessorData);
 
-  if (mPreviousSiblingData)
-    mPreviousSiblingData->Destroy(mPresContext);
-  if (mParentData)
-    mParentData->Destroy(mPresContext);
+  // Destroy potentially long chains of previous sibling and parent data
+  // without more than one level of recursion.
+  if (mPreviousSiblingData || mParentData) {
+    nsAutoVoidArray destroyQueue;
+    destroyQueue.AppendElement(this);
+
+    do {
+      RuleProcessorData *d = NS_STATIC_CAST(RuleProcessorData*,
+        destroyQueue.FastElementAt(destroyQueue.Count() - 1));
+      destroyQueue.RemoveElementAt(destroyQueue.Count() - 1);
+
+      if (d->mPreviousSiblingData) {
+        destroyQueue.AppendElement(d->mPreviousSiblingData);
+        d->mPreviousSiblingData = nsnull;
+      }
+      if (d->mParentData) {
+        destroyQueue.AppendElement(d->mParentData);
+        d->mParentData = nsnull;
+      }
+
+      if (d != this)
+        d->Destroy(mPresContext);
+    } while (destroyQueue.Count());
+  }
 
   delete mLanguage;
 }
diff --git a/layout/style/nsIStyleRuleProcessor.h b/layout/style/nsIStyleRuleProcessor.h
index fe7e8209f8f9..e473f559c7dd 100644
--- a/layout/style/nsIStyleRuleProcessor.h
+++ b/layout/style/nsIStyleRuleProcessor.h
@@ -99,6 +99,9 @@ struct RuleProcessorData {
   PRInt32           mEventState;    // if content, eventStateMgr->GetContentState()
   PRInt32           mNameSpaceID;   // if content, content->GetNameSapce()
   const nsAttrValue* mClasses;      // if styled content, styledcontent->GetClasses()
+  // mPreviousSiblingData and mParentData are always RuleProcessorData
+  // and never a derived class.  They are allocated lazily, when
+  // selectors require matching of prior siblings or ancestors.
   RuleProcessorData* mPreviousSiblingData;
   RuleProcessorData* mParentData;