diff --git a/components/style/sharing/mod.rs b/components/style/sharing/mod.rs
index 7eaf0322d6b..2cdd0913ae6 100644
--- a/components/style/sharing/mod.rs
+++ b/components/style/sharing/mod.rs
@@ -90,8 +90,15 @@ impl ValidationData {
         where E: TElement,
     {
         if self.class_list.is_none() {
-            let mut class_list = SmallVec::new();
+            let mut class_list = SmallVec::<[Atom; 5]>::new();
             element.each_class(|c| class_list.push(c.clone()));
+            // Assuming there are a reasonable number of classes (we use the
+            // inline capacity as "reasonable number"), sort them to so that
+            // we don't mistakenly reject sharing candidates when one element
+            // has "foo bar" and the other has "bar foo".
+            if !class_list.spilled() {
+                class_list.sort_by(|a, b| a.get_hash().cmp(&b.get_hash()));
+            }
             self.class_list = Some(class_list);
         }
         &*self.class_list.as_ref().unwrap()
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index def4de9eab1..48f369bd35b 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -966,7 +966,9 @@ impl Stylist {
                         assert_eq!(declaration.level, CascadeLevel::PresHints);
                     }
                 }
-                // Never share style for elements with preshints
+                // Note the existence of presentational attributes so that the
+                // style sharing cache can avoid re-querying them if they don't
+                // exist.
                 context.relations |= AFFECTED_BY_PRESENTATIONAL_HINTS;
             }
             debug!("preshints: {:?}", context.relations);