diff --git a/layout/base/RestyleManager.cpp b/layout/base/RestyleManager.cpp
index 591aa1d3e861..719c76f70e5e 100644
--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -2877,6 +2877,12 @@ ElementRestyler::Restyle(nsRestyleHint aRestyleHint)
     // to the style context (as is done by nsTransformedTextRun objects, which
     // can be referenced by a text frame's mTextRun longer than the frame's
     // mStyleContext).
+    //
+    // Also, we don't want this style context to get any more uses by being
+    // returned from nsStyleContext::FindChildWithRules, so we add the
+    // NS_STYLE_INELIGIBLE_FOR_SHARING bit to it.
+    oldContext->SetIneligibleForSharing();
+
     ContextToClear* toClear = mContextsToClear.AppendElement();
     toClear->mStyleContext = Move(oldContext);
     toClear->mStructs = swappedStructs;
diff --git a/layout/style/nsStyleContext.cpp b/layout/style/nsStyleContext.cpp
index 2b4f5c7c56e4..2a9ae073eecb 100644
--- a/layout/style/nsStyleContext.cpp
+++ b/layout/style/nsStyleContext.cpp
@@ -351,7 +351,7 @@ nsStyleContext::FindChildWithRules(const nsIAtom* aPseudoTag,
         } else {
           match = !child->GetStyleIfVisited();
         }
-        if (match) {
+        if (match && !(child->mBits & NS_STYLE_INELIGIBLE_FOR_SHARING)) {
           result = child;
           break;
         }
@@ -1404,6 +1404,29 @@ nsStyleContext::DoClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs)
   ClearCachedInheritedStyleDataOnDescendants(aStructs);
 }
 
+void
+nsStyleContext::SetIneligibleForSharing()
+{
+  if (mBits & NS_STYLE_INELIGIBLE_FOR_SHARING) {
+    return;
+  }
+  mBits |= NS_STYLE_INELIGIBLE_FOR_SHARING;
+  if (mChild) {
+    nsStyleContext* child = mChild;
+    do {
+      child->SetIneligibleForSharing();
+      child = child->mNextSibling;
+    } while (mChild != child);
+  }
+  if (mEmptyChild) {
+    nsStyleContext* child = mEmptyChild;
+    do {
+      child->SetIneligibleForSharing();
+      child = child->mNextSibling;
+    } while (mEmptyChild != child);
+  }
+}
+
 #ifdef RESTYLE_LOGGING
 nsCString
 nsStyleContext::GetCachedStyleDataAsString(uint32_t aStructs)
diff --git a/layout/style/nsStyleContext.h b/layout/style/nsStyleContext.h
index f0cf8e418598..33ba5699a3a1 100644
--- a/layout/style/nsStyleContext.h
+++ b/layout/style/nsStyleContext.h
@@ -431,6 +431,13 @@ public:
    */
   void ClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs);
 
+  /**
+   * Sets the NS_STYLE_INELIGIBLE_FOR_SHARING bit on this style context
+   * and its descendants.  If it finds a descendant that has the bit
+   * already set, assumes that it can skip that subtree.
+   */
+  void SetIneligibleForSharing();
+
 #ifdef DEBUG
   void List(FILE* out, int32_t aIndent, bool aListDescendants = true);
   static void AssertStyleStructMaxDifferenceValid();
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 2678c8ed6edf..a122b7ec6776 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -60,8 +60,10 @@ class imgIContainer;
 #define NS_STYLE_SUPPRESS_LINEBREAK        0x080000000
 // See nsStyleContext::IsInDisplayNoneSubtree
 #define NS_STYLE_IN_DISPLAY_NONE_SUBTREE   0x100000000
+// See nsStyleContext::FindChildWithRules
+#define NS_STYLE_INELIGIBLE_FOR_SHARING    0x200000000
 // See nsStyleContext::GetPseudoEnum
-#define NS_STYLE_CONTEXT_TYPE_SHIFT        33
+#define NS_STYLE_CONTEXT_TYPE_SHIFT        34
 
 // Additional bits for nsRuleNode's mDependentBits:
 #define NS_RULE_NODE_GC_MARK                0x02000000
diff --git a/layout/style/test/chrome/chrome.ini b/layout/style/test/chrome/chrome.ini
index 5faaf82ffa19..7016d8561755 100644
--- a/layout/style/test/chrome/chrome.ini
+++ b/layout/style/test/chrome/chrome.ini
@@ -9,6 +9,7 @@ support-files =
 [test_addSheet.html]
 [test_additional_sheets.html]
 [test_author_specified_style.html]
+[test_bug1157097.html]
 [test_bug535806.xul]
 [test_hover.html]
 skip-if = buildapp == 'mulet'
diff --git a/layout/style/test/chrome/test_bug1157097.html b/layout/style/test/chrome/test_bug1157097.html
new file mode 100644
index 000000000000..748a9eed2dae
--- /dev/null
+++ b/layout/style/test/chrome/test_bug1157097.html
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<title>Test for bug 1157097</title>
+<script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css">
+<style>
+.blue { color: blue; }
+.red { color: red; }
+.inline-block { display: inline-block; }
+</style>
+<body onload=run()>
+<p><span id=s1 class=blue><b></b></span><span id=s2 class=red><b></b></span></p>
+<script>
+var Ci = Components.interfaces;
+var windowUtils = window.QueryInterface(Ci.nsIInterfaceRequestor)
+                     .getInterface(Ci.nsIDOMWindowUtils);
+
+function run() {
+  windowUtils.postRestyleSelfEvent(document.querySelector("p"));
+  document.querySelectorAll("span")[0].className = "";
+  document.querySelectorAll("b")[0].className = "inline-block";
+  document.querySelectorAll("span")[1].className = "blue";
+  windowUtils.postRestyleSelfEvent(document.querySelectorAll("b")[1]);
+
+  document.body.offsetTop;
+
+  ok(true, "finished (hopefully we didn't assert)");
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+</script>