diff --git a/components/script/layout_wrapper.rs b/components/script/layout_wrapper.rs
index 8838787defc..a6d4815090f 100644
--- a/components/script/layout_wrapper.rs
+++ b/components/script/layout_wrapper.rs
@@ -477,6 +477,10 @@ impl<'le> TElement for ServoLayoutElement<'le> {
             })
         }
     }
+
+    fn skip_root_and_item_based_display_fixup(&self) -> bool {
+        false
+    }
 }
 
 impl<'le> PartialEq for ServoLayoutElement<'le> {
diff --git a/components/style/dom.rs b/components/style/dom.rs
index da476cedbaf..5c66bbc0e0f 100644
--- a/components/style/dom.rs
+++ b/components/style/dom.rs
@@ -269,4 +269,9 @@ pub trait TElement : PartialEq + Debug + Sized + Copy + Clone + ElementExt + Pre
     fn mutate_data(&self) -> Option<AtomicRefMut<ElementData>> {
         self.get_data().map(|x| x.borrow_mut())
     }
+
+    /// Whether we should skip any root- or item-based display property
+    /// blockification on this element.  (This function exists so that Gecko
+    /// native anonymous content can opt out of this style fixup.)
+    fn skip_root_and_item_based_display_fixup(&self) -> bool;
 }
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index 5a8c462db9e..6b124d55d20 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -371,6 +371,15 @@ impl<'le> TElement for GeckoElement<'le> {
     fn get_data(&self) -> Option<&AtomicRefCell<ElementData>> {
         unsafe { self.0.mServoData.get().as_ref() }
     }
+
+    fn skip_root_and_item_based_display_fixup(&self) -> bool {
+        // We don't want to fix up display values of native anonymous content.
+        // Additionally, we want to skip root-based display fixup for document
+        // level native anonymous content subtree roots, since they're not
+        // really roots from the style fixup perspective.  Checking that we
+        // are NAC handles both cases.
+        self.flags() & (NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE as u32) != 0
+    }
 }
 
 impl<'le> PartialEq for GeckoElement<'le> {
diff --git a/components/style/matching.rs b/components/style/matching.rs
index e883d11bc3e..3b0a396507d 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -14,7 +14,7 @@ use cascade_info::CascadeInfo;
 use context::{SharedStyleContext, StyleContext};
 use data::{ComputedStyle, ElementData, ElementStyles, PseudoStyles};
 use dom::{TElement, TNode, TRestyleDamage, UnsafeNode};
-use properties::{CascadeFlags, ComputedValues, SHAREABLE, cascade};
+use properties::{CascadeFlags, ComputedValues, SHAREABLE, SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP, cascade};
 use properties::longhands::display::computed_value as display;
 use rule_tree::StrongRuleNode;
 use selector_parser::{PseudoElement, RestyleDamage, SelectorImpl};
@@ -405,6 +405,9 @@ trait PrivateMatchMethods: TElement {
         if booleans.shareable {
             cascade_flags.insert(SHAREABLE)
         }
+        if self.skip_root_and_item_based_display_fixup() {
+            cascade_flags.insert(SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP)
+        }
 
         let this_style = match parent_style {
             Some(ref parent_style) => {
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index c80665a0af6..46688434651 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -1436,6 +1436,8 @@ bitflags! {
         /// Whether to inherit all styles from the parent. If this flag is not present,
         /// non-inherited styles are reset to their initial values.
         const INHERIT_ALL = 0x02,
+        /// Whether to skip any root element and flex/grid item display style fixup.
+        const SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP = 0x04,
     }
 }
 
@@ -1638,7 +1640,11 @@ pub fn apply_declarations<'a, F, I>(viewport_size: Size2D<Au>,
         computed_values::display::T::grid |
         % endif
         computed_values::display::T::flex);
-    if positioned || floated || is_root_element || is_item {
+    let (blockify_root, blockify_item) = match flags.contains(SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP) {
+        false => (is_root_element, is_item),
+        true => (false, false),
+    };
+    if positioned || floated || blockify_root || blockify_item {
         use computed_values::display::T;
 
         let specified_display = style.get_box().clone_display();
@@ -1653,7 +1659,7 @@ pub fn apply_declarations<'a, F, I>(viewport_size: Size2D<Au>,
 
             // Special handling for contents and list-item on the root element for Gecko.
             % if product == "gecko":
-            T::contents | T::list_item if is_root_element => Some(T::block),
+            T::contents | T::list_item if blockify_root => Some(T::block),
             % endif
 
             // Values that are not changed by blockification.
@@ -1669,7 +1675,7 @@ pub fn apply_declarations<'a, F, I>(viewport_size: Size2D<Au>,
             let box_ = style.mutate_box();
             box_.set_display(computed_display);
             % if product == "servo":
-                box_.set__servo_display_for_hypothetical_box(if is_root_element || is_item {
+                box_.set__servo_display_for_hypothetical_box(if blockify_root || blockify_item {
                     computed_display
                 } else {
                     specified_display