diff --git a/gfx/layers/apz/src/AsyncPanZoomController.cpp b/gfx/layers/apz/src/AsyncPanZoomController.cpp
index e9083cd54704..631a84979165 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.cpp
+++ b/gfx/layers/apz/src/AsyncPanZoomController.cpp
@@ -89,6 +89,7 @@
 #include "ScrollSnap.h"              // for ScrollSnapUtils
 #include "ScrollAnimationPhysics.h"  // for ComputeAcceleratedWheelDelta
 #include "SmoothMsdScrollAnimation.h"
+#include "SmoothScrollAnimation.h"
 #include "WheelScrollAnimation.h"
 #include "KeyboardScrollAnimation.h"
 #if defined(MOZ_WIDGET_ANDROID)
@@ -1219,6 +1220,7 @@ nsEventStatus AsyncPanZoomController::OnTouchStart(
   switch (mState) {
     case FLING:
     case ANIMATING_ZOOM:
+    case SMOOTH_SCROLL:
     case SMOOTHMSD_SCROLL:
     case OVERSCROLL_ANIMATION:
     case WHEEL_SCROLL:
@@ -1314,6 +1316,7 @@ nsEventStatus AsyncPanZoomController::OnTouchMove(
           "Gesture listener should have handled pinching in OnTouchMove.");
       return nsEventStatus_eIgnore;
 
+    case SMOOTH_SCROLL:
     case WHEEL_SCROLL:
     case KEYBOARD_SCROLL:
     case OVERSCROLL_ANIMATION:
@@ -1398,6 +1401,7 @@ nsEventStatus AsyncPanZoomController::OnTouchEnd(
           "Gesture listener should have handled pinching in OnTouchEnd.");
       return nsEventStatus_eIgnore;
 
+    case SMOOTH_SCROLL:
     case WHEEL_SCROLL:
     case KEYBOARD_SCROLL:
     case OVERSCROLL_ANIMATION:
@@ -3310,6 +3314,9 @@ Maybe<CSSPoint> AsyncPanZoomController::GetCurrentAnimationDestination(
   if (mState == WHEEL_SCROLL) {
     return Some(mAnimation->AsWheelScrollAnimation()->GetDestination());
   }
+  if (mState == SMOOTH_SCROLL) {
+    return Some(mAnimation->AsSmoothScrollAnimation()->GetDestination());
+  }
   if (mState == SMOOTHMSD_SCROLL) {
     return Some(mAnimation->AsSmoothMsdScrollAnimation()->GetDestination());
   }
@@ -3379,6 +3386,36 @@ void AsyncPanZoomController::HandleSmoothScrollOverscroll(
   HandleFlingOverscroll(aVelocity, BuildOverscrollHandoffChain(), nullptr);
 }
 
+void AsyncPanZoomController::SmoothScrollTo(const CSSPoint& aDestination,
+                                            const ScrollOrigin& aOrigin) {
+  // Convert velocity from ParentLayerPoints/ms to ParentLayerPoints/s and then
+  // to appunits/second.
+  nsPoint destination = CSSPoint::ToAppUnits(aDestination);
+  nsSize velocity = CSSSize::ToAppUnits(
+      ParentLayerSize(mX.GetVelocity() * 1000.0f, mY.GetVelocity() * 1000.0f) /
+      Metrics().GetZoom());
+
+  if (mState == SMOOTH_SCROLL && mAnimation) {
+    RefPtr<SmoothScrollAnimation> animation(
+        mAnimation->AsSmoothScrollAnimation());
+    if (animation->GetScrollOrigin() == aOrigin) {
+      APZC_LOG("%p updating destination on existing animation\n", this);
+      animation->UpdateDestination(GetFrameTime().Time(), destination,
+                                   velocity);
+      return;
+    }
+  }
+
+  CancelAnimation();
+  SetState(SMOOTH_SCROLL);
+  nsPoint initialPosition =
+      CSSPoint::ToAppUnits(Metrics().GetVisualScrollOffset());
+  RefPtr<SmoothScrollAnimation> animation =
+      new SmoothScrollAnimation(*this, initialPosition, aOrigin);
+  animation->UpdateDestination(GetFrameTime().Time(), destination, velocity);
+  StartAnimation(animation.get());
+}
+
 void AsyncPanZoomController::SmoothMsdScrollTo(const CSSPoint& aDestination) {
   if (mState == SMOOTHMSD_SCROLL && mAnimation) {
     APZC_LOG("%p updating destination on existing animation\n", this);
@@ -4625,7 +4662,12 @@ void AsyncPanZoomController::NotifyLayersUpdated(
         destination = scrollUpdate.GetDestination();
       }
 
-      SmoothMsdScrollTo(destination);
+      if (scrollUpdate.GetMode() == ScrollMode::SmoothMsd) {
+        SmoothMsdScrollTo(destination);
+      } else {
+        MOZ_ASSERT(scrollUpdate.GetMode() == ScrollMode::Smooth);
+        SmoothScrollTo(destination, scrollUpdate.GetOrigin());
+      }
       continue;
     }
 
diff --git a/gfx/layers/apz/src/AsyncPanZoomController.h b/gfx/layers/apz/src/AsyncPanZoomController.h
index 07b918dcb8be..e7fb4a61587f 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.h
+++ b/gfx/layers/apz/src/AsyncPanZoomController.h
@@ -1239,6 +1239,8 @@ class AsyncPanZoomController {
     ANIMATING_ZOOM,       /* animated zoom to a new rect */
     OVERSCROLL_ANIMATION, /* Spring-based animation used to relieve overscroll
                              once the finger is lifted. */
+    SMOOTH_SCROLL,        /* Smooth scrolling to destination, with physics
+                             controlled by prefs specific to the scroll origin. */
     SMOOTHMSD_SCROLL,     /* SmoothMSD scrolling to destination. Used by
                              CSSOM-View smooth scroll-behavior */
     WHEEL_SCROLL,    /* Smooth scrolling to a destination for a wheel event. */
@@ -1401,6 +1403,11 @@ class AsyncPanZoomController {
   // Start an overscroll animation with the given initial velocity.
   void StartOverscrollAnimation(const ParentLayerPoint& aVelocity);
 
+  // Start a smooth-scrolling animation to the given destination, with physics
+  // based on the prefs for the indicated origin.
+  void SmoothScrollTo(const CSSPoint& aDestination,
+                      const ScrollOrigin& aOrigin);
+
   // Start a smooth-scrolling animation to the given destination, with MSD
   // physics that is suited for scroll-snapping.
   void SmoothMsdScrollTo(const CSSPoint& aDestination);