--- a/layout/style/Loader.cpp
+++ b/layout/style/Loader.cpp
@@ -2201,18 +2201,16 @@ Loader::LoadChildSheet(StyleSheet* aPare
                        ImportRule* aGeckoParentRule,
                        const RawServoStyleSheet* aServoChildSheet,
                        LoaderReusableStyleSheets* aReusableSheets)
 {
   LOG(("css::Loader::LoadChildSheet"));
   NS_PRECONDITION(aURL, "Must have a URI to load");
   NS_PRECONDITION(aParentSheet, "Must have a parent sheet");
 
-  // Servo doesn't support reusable sheets.
-  MOZ_ASSERT_IF(aReusableSheets, aParentSheet->IsGecko());
   MOZ_ASSERT_IF(aParentSheet->IsGecko(), aGeckoParentRule && !aServoChildSheet);
   MOZ_ASSERT_IF(aParentSheet->IsServo(), aServoChildSheet && !aGeckoParentRule);
 
   if (!mEnabled) {
     LOG_WARN(("  Not enabled"));
     return NS_ERROR_NOT_AVAILABLE;
   }
 

--- a/layout/style/ServoBindingList.h
+++ b/layout/style/ServoBindingList.h
@@ -35,17 +35,18 @@ SERVO_BINDING_FUNC(Servo_StyleSheet_From
                    nsCompatibility quirks_mode)
 SERVO_BINDING_FUNC(Servo_StyleSheet_ClearAndUpdate,
                    void,
                    RawServoStyleSheetBorrowed stylesheet,
                    mozilla::css::Loader* loader,
                    mozilla::ServoStyleSheet* gecko_stylesheet,
                    const nsACString* data,
                    RawGeckoURLExtraData* extra_data,
-                   uint32_t line_number_offset)
+                   uint32_t line_number_offset,
+                   mozilla::css::LoaderReusableStyleSheets* reusable_sheets)
 SERVO_BINDING_FUNC(Servo_StyleSheet_HasRules, bool,
                    RawServoStyleSheetBorrowed sheet)
 SERVO_BINDING_FUNC(Servo_StyleSheet_GetRules, ServoCssRulesStrong,
                    RawServoStyleSheetBorrowed sheet)
 SERVO_BINDING_FUNC(Servo_StyleSheet_Clone, RawServoStyleSheetStrong,
                    RawServoStyleSheetBorrowed sheet)
 SERVO_BINDING_FUNC(Servo_StyleSheet_SizeOfIncludingThis, size_t,
                    mozilla::MallocSizeOf malloc_size_of, RawServoStyleSheetBorrowed sheet)

--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -2182,16 +2182,17 @@ Gecko_GetAppUnitsPerPhysicalInch(RawGeck
 {
   nsPresContext* presContext = const_cast<nsPresContext*>(aPresContext);
   return presContext->DeviceContext()->AppUnitsPerPhysicalInch();
 }
 
 void
 Gecko_LoadStyleSheet(css::Loader* aLoader,
                      ServoStyleSheet* aParent,
+                     css::LoaderReusableStyleSheets* aReusableSheets,
                      RawServoStyleSheetBorrowed aChildSheet,
                      RawGeckoURLExtraData* aBaseURLData,
                      const uint8_t* aURLString,
                      uint32_t aURLStringLength,
                      RawServoMediaListStrong aMediaList)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(aLoader, "Should've catched this before");
@@ -2209,17 +2210,17 @@ Gecko_LoadStyleSheet(css::Loader* aLoade
   if (NS_FAILED(rv)) {
     // Servo and Gecko have different ideas of what a valid URL is, so we might
     // get in here with a URL string that NS_NewURI can't handle.  If so,
     // silently do nothing.  Eventually we should be able to assert that the
     // NS_NewURI succeeds, here.
     return;
   }
 
-  aLoader->LoadChildSheet(aParent, uri, media, nullptr, aChildSheet, nullptr);
+  aLoader->LoadChildSheet(aParent, uri, media, nullptr, aChildSheet, aReusableSheets);
 }
 
 const nsMediaFeature*
 Gecko_GetMediaFeatures()
 {
   return nsMediaFeatures::features;
 }
 

--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -37,16 +37,17 @@ namespace mozilla {
   enum FontFamilyType : uint32_t;
   enum class CSSPseudoElementType : uint8_t;
   struct Keyframe;
   enum Side;
   struct StyleTransition;
   namespace css {
     struct URLValue;
     struct ImageValue;
+    class LoaderReusableStyleSheets;
   };
   namespace dom {
     enum class IterationCompositeOperation : uint8_t;
   };
   enum class UpdateAnimationsTasks : uint8_t;
   struct LangGroupFontPrefs;
   class ServoStyleSheet;
   class ServoElementSnapshotTable;
@@ -132,16 +133,17 @@ RawGeckoNodeBorrowedOrNull Gecko_GetPrev
 RawGeckoNodeBorrowedOrNull Gecko_GetNextSibling(RawGeckoNodeBorrowed node);
 RawGeckoElementBorrowedOrNull Gecko_GetFirstChildElement(RawGeckoElementBorrowed element);
 RawGeckoElementBorrowedOrNull Gecko_GetLastChildElement(RawGeckoElementBorrowed element);
 RawGeckoElementBorrowedOrNull Gecko_GetPrevSiblingElement(RawGeckoElementBorrowed element);
 RawGeckoElementBorrowedOrNull Gecko_GetNextSiblingElement(RawGeckoElementBorrowed element);
 RawGeckoElementBorrowedOrNull Gecko_GetDocumentElement(RawGeckoDocumentBorrowed document);
 void Gecko_LoadStyleSheet(mozilla::css::Loader* loader,
                           mozilla::ServoStyleSheet* parent,
+                          mozilla::css::LoaderReusableStyleSheets* reusable_sheets,
                           RawServoStyleSheetBorrowed child_sheet,
                           RawGeckoURLExtraData* base_url_data,
                           const uint8_t* url_bytes,
                           uint32_t url_length,
                           RawServoMediaListStrong media_list);
 
 // By default, Servo walks the DOM by traversing the siblings of the DOM-view
 // first child. This generally works, but misses anonymous children, which we

--- a/layout/style/ServoBindings.toml
+++ b/layout/style/ServoBindings.toml
@@ -42,16 +42,17 @@ args = [
 
 [structs]
 headers = [
     "nsStyleStruct.h",
     "mozilla/ServoPropPrefList.h",
     "mozilla/StyleAnimationValue.h",
     "gfxFontConstants.h",
     "nsThemeConstants.h",
+    "mozilla/css/Loader.h",
     "mozilla/dom/AnimationEffectReadOnlyBinding.h",
     "mozilla/dom/KeyframeEffectBinding.h",
     "mozilla/AnimationPropertySegment.h",
     "mozilla/ComputedTiming.h",
     "mozilla/ComputedTimingFunction.h",
     "mozilla/Keyframe.h",
     "mozilla/ServoElementSnapshot.h",
     "mozilla/ServoElementSnapshotTable.h",
@@ -422,16 +423,17 @@ structs-types = [
     "nsStyleVariables",
     "nsStyleVisibility",
     "nsStyleXUL",
     "nsTimingFunction",
     "nscolor",
     "nscoord",
     "nsresult",
     "Loader",
+    "LoaderReusableStyleSheets",
     "ServoStyleSheet",
     "EffectCompositor_CascadeLevel",
     "UpdateAnimationsTasks",
     "ParsingMode",
     "InheritTarget",
     "URLMatchingFunction",
     "StyleRuleInclusion",
 ]

--- a/layout/style/ServoStyleSheet.cpp
+++ b/layout/style/ServoStyleSheet.cpp
@@ -9,16 +9,17 @@
 #include "mozilla/css/Rule.h"
 #include "mozilla/StyleBackendType.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/ServoMediaList.h"
 #include "mozilla/ServoCSSRuleList.h"
 #include "mozilla/css/GroupRule.h"
 #include "mozilla/dom/CSSRuleList.h"
 #include "mozilla/dom/MediaList.h"
+#include "Loader.h"
 
 
 #include "mozAutoDocUpdate.h"
 #include "nsIDOMCSSStyleSheet.h"
 
 using namespace mozilla::dom;
 
 namespace mozilla {
@@ -136,17 +137,18 @@ ServoStyleSheet::HasRules() const
 
 nsresult
 ServoStyleSheet::ParseSheet(css::Loader* aLoader,
                             const nsAString& aInput,
                             nsIURI* aSheetURI,
                             nsIURI* aBaseURI,
                             nsIPrincipal* aSheetPrincipal,
                             uint32_t aLineNumber,
-                            nsCompatibility aCompatMode)
+                            nsCompatibility aCompatMode,
+                            css::LoaderReusableStyleSheets* aReusableSheets)
 {
   MOZ_ASSERT_IF(mMedia, mMedia->IsServo());
   RefPtr<URLExtraData> extraData =
     new URLExtraData(aBaseURI, aSheetURI, aSheetPrincipal);
 
   NS_ConvertUTF16toUTF8 input(aInput);
   if (!Inner()->mSheet) {
     auto* mediaList = static_cast<ServoMediaList*>(mMedia.get());
@@ -157,17 +159,18 @@ ServoStyleSheet::ParseSheet(css::Loader*
           aLoader, this, &input, mParsingMode, media, extraData,
           aLineNumber, aCompatMode
       ).Consume();
   } else {
     // TODO(emilio): Once we have proper inner cloning (which we don't right
     // now) we should update the mediaList here too, though it's slightly
     // tricky.
     Servo_StyleSheet_ClearAndUpdate(Inner()->mSheet, aLoader,
-                                    this, &input, extraData, aLineNumber);
+                                    this, &input, extraData, aLineNumber,
+                                    aReusableSheets);
   }
 
   Inner()->mURLData = extraData.forget();
   return NS_OK;
 }
 
 void
 ServoStyleSheet::LoadFailed()

--- a/layout/style/ServoStyleSheet.h
+++ b/layout/style/ServoStyleSheet.h
@@ -17,16 +17,17 @@
 #include "nsStringFwd.h"
 
 namespace mozilla {
 
 class ServoCSSRuleList;
 
 namespace css {
 class Loader;
+class LoaderReusableStyleSheets;
 }
 
 // -------------------------------
 // Servo Style Sheet Inner Data Container
 //
 
 struct ServoStyleSheetInner : public StyleSheetInfo
 {
@@ -79,17 +80,18 @@ public:
   bool HasRules() const;
 
   MOZ_MUST_USE nsresult ParseSheet(css::Loader* aLoader,
                                    const nsAString& aInput,
                                    nsIURI* aSheetURI,
                                    nsIURI* aBaseURI,
                                    nsIPrincipal* aSheetPrincipal,
                                    uint32_t aLineNumber,
-                                   nsCompatibility aCompatMode);
+                                   nsCompatibility aCompatMode,
+                                   css::LoaderReusableStyleSheets* aReusableSheets = nullptr);
 
   /**
    * Called instead of ParseSheet to initialize the Servo stylesheet object
    * for a failed load. Either ParseSheet or LoadFailed must be called before
    * adding a ServoStyleSheet to a ServoStyleSet.
    */
   void LoadFailed();