diff --git a/layout/style/nsCSSDataBlock.cpp b/layout/style/nsCSSDataBlock.cpp
index e6045451d8..09ac37550e 100644
--- a/layout/style/nsCSSDataBlock.cpp
+++ b/layout/style/nsCSSDataBlock.cpp
@@ -174,7 +174,8 @@ MapSinglePropertyInto(nsCSSPropertyID aTargetProp,
   // then records any resulting ImageValue objects in the
   // CSSVariableImageTable, to give them the appropriate lifetime.
   MOZ_ASSERT(aTargetValue->GetUnit() == eCSSUnit_TokenStream ||
-             aTargetValue->GetUnit() == eCSSUnit_Null,
+             aTargetValue->GetUnit() == eCSSUnit_Null ||
+             aTargetValue->GetUnit() == eCSSUnit_Revert,
              "aTargetValue must only be a token stream (when re-parsing "
              "properties with variable references) or null");
 
@@ -316,19 +317,26 @@ nsCSSCompressedDataBlock::MapRuleInfoInto(nsRuleData *aRuleData) const
         EnsurePhysicalProperty(iProp, aRuleData);
       }
       nsCSSValue* target = aRuleData->ValueFor(iProp);
-      if (target->GetUnit() == eCSSUnit_Null) {
-        const nsCSSValue *val = ValueAtIndex(i);
-        // In order for variable resolution to have the right information
-        // about the stylesheet level of a value, that level needs to be
-        // stored on the token stream. We can't do that at creation time
-        // because the CSS parser (which creates the object) has no idea
-        // about the stylesheet level, so we do it here instead, where
-        // the rule walking will have just updated aRuleData.
-        if (val->GetUnit() == eCSSUnit_TokenStream) {
-          val->GetTokenStreamValue()->mLevel = aRuleData->mLevel;
+      if (target->GetUnit() == eCSSUnit_Revert) {
+        if (aRuleData->mLevel >= target->GetCascadeOriginValue()) {
+          continue;
         }
-        MapSinglePropertyInto(iProp, val, target, aRuleData);
+      } else if (target->GetUnit() != eCSSUnit_Null) {
+        continue;
       }
+      const nsCSSValue* val = ValueAtIndex(i);
+      // In order for variable resolution to have the right information
+      // about the stylesheet level of a value, that level needs to be
+      // stored on the token stream. We can't do that at creation time
+      // because the CSS parser (which creates the object) has no idea
+      // about the stylesheet level, so we do it here instead, where
+      // the rule walking will have just updated aRuleData.
+      if (val->GetUnit() == eCSSUnit_TokenStream) {
+        val->GetTokenStreamValue()->mLevel = aRuleData->mLevel;
+      } else if (val->GetUnit() == eCSSUnit_Revert) {
+        aRuleData->mConditions.SetUncacheable();
+      }
+      MapSinglePropertyInto(iProp, val, target, aRuleData);
     }
   }
 }
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 668debb5cb..33c8ad5fa4 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -2248,7 +2248,8 @@ AreAllMathMLPropertiesUndefined(const nsRuleData* aRuleData)
 
 inline nsRuleNode::RuleDetail
 nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
-                                     const nsRuleData* aRuleData)
+                                     const nsRuleData* aRuleData,
+                                     bool& ignoreRuleCache)
 {
   // Build a count of the:
   uint32_t total = 0,      // total number of props in the struct
@@ -2323,6 +2324,8 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
     result = (*cb)(aRuleData, result);
   }
 
+  ignoreRuleCache = revert > 0;
+
   return result;
 }
 
@@ -2491,6 +2494,7 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
                                // will be the root.  (XXX misnamed)
   RuleDetail detail = eRuleNone;
   uint32_t bit = nsCachedStyleData::GetBitForSID(aSID);
+  bool ignoreRuleCache = false;
 
   while (ruleNode) {
     // See if this rule node has cached the fact that the remaining
@@ -2517,9 +2521,16 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
     // we'll miss it.
     startStruct = ruleNode->mStyleData.GetStyleData(aSID);
     if (startStruct) {
-      break; // We found a rule with fully specified data.  We don't
-    }        // need to go up the tree any further, since the remainder
-             // of this branch has already been computed.
+      // XXX: Ignore cached data if the previous rule node has revert values.
+      if (ignoreRuleCache) {
+        startStruct = nullptr;
+      } else {
+        // We found a rule with fully specified data.  We don't
+        // need to go up the tree any further, since the remainder
+        // of this branch has already been computed.
+        break;
+      }
+    }
 
     // Ask the rule to fill in the properties that it specifies.
     nsIStyleRule *rule = ruleNode->mRule;
@@ -2532,15 +2543,15 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
     // Now we check to see how many properties have been specified by
     // the rules we've examined so far.
     RuleDetail oldDetail = detail;
-    detail = CheckSpecifiedProperties(aSID, &ruleData);
+    detail = CheckSpecifiedProperties(aSID, &ruleData, ignoreRuleCache);
 
-    if (oldDetail == eRuleNone && detail != eRuleNone) {
+    if (oldDetail == eRuleNone && (detail != eRuleNone || ignoreRuleCache)) {
       highestNode = ruleNode;
     }
 
-    if (detail == eRuleFullReset ||
-        detail == eRuleFullMixed ||
-        detail == eRuleFullInherited) {
+    if (!ignoreRuleCache && (detail == eRuleFullReset ||
+                             detail == eRuleFullMixed ||
+                             detail == eRuleFullInherited)) {
       break; // We don't need to examine any more rules.  All properties
     }        // have been fully specified.
 
@@ -2576,7 +2587,7 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
   }
 
   if (recomputeDetail) {
-    detail = CheckSpecifiedProperties(aSID, &ruleData);
+    detail = CheckSpecifiedProperties(aSID, &ruleData, ignoreRuleCache);
   }
 
   NS_ASSERTION(!startStruct || (detail != eRuleFullReset &&
@@ -10804,7 +10815,8 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
           for (uint32_t i = 0; i < nValues; ++i) {
             if (values[i]->GetUnit() != eCSSUnit_Null &&
                 values[i]->GetUnit() != eCSSUnit_Dummy && // see above
-                values[i]->GetUnit() != eCSSUnit_DummyInherit) {
+                values[i]->GetUnit() != eCSSUnit_DummyInherit &&
+                values[i]->GetUnit() != eCSSUnit_Revert) {
               // If author colors are not allowed, only claim to have
               // author-specified rules if we're looking at a non-color
               // property or if we're looking at the background color and it's
diff --git a/layout/style/nsRuleNode.h b/layout/style/nsRuleNode.h
index 49fa8a027b..7ca3a165f9 100644
--- a/layout/style/nsRuleNode.h
+++ b/layout/style/nsRuleNode.h
@@ -787,7 +787,8 @@ protected:
                              nsStyleFont* aFont);
 
   inline RuleDetail CheckSpecifiedProperties(const nsStyleStructID aSID,
-                                             const nsRuleData* aRuleData);
+                                             const nsRuleData* aRuleData,
+                                             bool& ignoreRuleCache);
 
 private:
   nsRuleNode(nsPresContext* aPresContext, nsRuleNode* aParent,