diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index c211c7b..b10d437 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -1719,10 +1719,55 @@
     mCurrentState.sequence++;
     mCurrentState.z = z;
     mCurrentState.modified = true;
+
+    // Discard all relative layering.
+    if (mCurrentState.zOrderRelativeOf != nullptr) {
+        sp<Layer> strongRelative = mCurrentState.zOrderRelativeOf.promote();
+        if (strongRelative != nullptr) {
+            strongRelative->removeZOrderRelative(this);
+        }
+        mCurrentState.zOrderRelativeOf = nullptr;
+    }
     setTransactionFlags(eTransactionNeeded);
     return true;
 }
 
+void Layer::removeZOrderRelative(const wp<Layer>& relative) {
+    mCurrentState.zOrderRelatives.remove(relative);
+    mCurrentState.sequence++;
+    mCurrentState.modified = true;
+    setTransactionFlags(eTransactionNeeded);
+}
+
+void Layer::addZOrderRelative(const wp<Layer>& relative) {
+    mCurrentState.zOrderRelatives.add(relative);
+    mCurrentState.modified = true;
+    mCurrentState.sequence++;
+    setTransactionFlags(eTransactionNeeded);
+}
+
+bool Layer::setRelativeLayer(const sp<IBinder>& relativeToHandle, int32_t z) {
+    sp<Handle> handle = static_cast<Handle*>(relativeToHandle.get());
+    if (handle == nullptr) {
+        return false;
+    }
+    sp<Layer> relative = handle->owner.promote();
+    if (relative == nullptr) {
+        return false;
+    }
+
+    mCurrentState.sequence++;
+    mCurrentState.modified = true;
+    mCurrentState.z = z;
+
+    mCurrentState.zOrderRelativeOf = relative;
+    relative->addZOrderRelative(this);
+
+    setTransactionFlags(eTransactionNeeded);
+
+    return true;
+}
+
 bool Layer::setSize(uint32_t w, uint32_t h) {
     if (mCurrentState.requested.w == w && mCurrentState.requested.h == h)
         return false;
@@ -2506,40 +2551,70 @@
     return mDrawingState.z;
 }
 
+LayerVector Layer::makeTraversalList() {
+    if (mDrawingState.zOrderRelatives.size() == 0) {
+        return mDrawingChildren;
+    }
+    LayerVector traverse;
+
+    for (const wp<Layer>& weakRelative : mDrawingState.zOrderRelatives) {
+        sp<Layer> strongRelative = weakRelative.promote();
+        if (strongRelative != nullptr) {
+            traverse.add(strongRelative);
+        } else {
+            // We need to erase from current state instead of drawing
+            // state so we don't overwrite when copying
+            // the current state to the drawing state.
+            mCurrentState.zOrderRelatives.remove(weakRelative);
+        }
+    }
+
+    for (const sp<Layer>& child : mDrawingChildren) {
+        traverse.add(child);
+    }
+
+    return traverse;
+}
+
 /**
- * Negatively signed children are before 'this' in Z-order.
+ * Negatively signed relatives are before 'this' in Z-order.
  */
 void Layer::traverseInZOrder(const std::function<void(Layer*)>& exec) {
+    LayerVector list = makeTraversalList();
+
     size_t i = 0;
-    for (; i < mDrawingChildren.size(); i++) {
-        const auto& child = mDrawingChildren[i];
-        if (child->getZ() >= 0)
+    for (; i < list.size(); i++) {
+        const auto& relative = list[i];
+        if (relative->getZ() >= 0) {
             break;
-        child->traverseInZOrder(exec);
+        }
+        relative->traverseInZOrder(exec);
     }
     exec(this);
-    for (; i < mDrawingChildren.size(); i++) {
-        const auto& child = mDrawingChildren[i];
-        child->traverseInZOrder(exec);
+    for (; i < list.size(); i++) {
+        const auto& relative = list[i];
+        relative->traverseInZOrder(exec);
     }
 }
 
 /**
- * Positively signed children are before 'this' in reverse Z-order.
+ * Positively signed relatives are before 'this' in reverse Z-order.
  */
 void Layer::traverseInReverseZOrder(const std::function<void(Layer*)>& exec) {
+    LayerVector list = makeTraversalList();
+
     int32_t i = 0;
-    for (i = mDrawingChildren.size()-1; i>=0; i--) {
-        const auto& child = mDrawingChildren[i];
-        if (child->getZ() < 0) {
+    for (i = list.size()-1; i>=0; i--) {
+        const auto& relative = list[i];
+        if (relative->getZ() < 0) {
             break;
         }
-        child->traverseInReverseZOrder(exec);
+        relative->traverseInReverseZOrder(exec);
     }
     exec(this);
     for (; i>=0; i--) {
-        const auto& child = mDrawingChildren[i];
-        child->traverseInReverseZOrder(exec);
+        const auto& relative = list[i];
+        relative->traverseInReverseZOrder(exec);
     }
 }
 
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index e21be8b..a5224ec 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -151,6 +151,12 @@
 
         uint32_t appId;
         uint32_t type;
+
+        // If non-null, a Surface this Surface's Z-order is interpreted relative to.
+        wp<Layer> zOrderRelativeOf;
+
+        // A list of surfaces whose Z-order is interpreted relative to ours.
+        SortedVector<wp<Layer>> zOrderRelatives;
     };
 
     // -----------------------------------------------------------------------
@@ -173,6 +179,8 @@
     bool setFinalCrop(const Rect& crop, bool immediate);
 
     bool setLayer(int32_t z);
+    bool setRelativeLayer(const sp<IBinder>& relativeToHandle, int32_t relativeZ);
+
     bool setSize(uint32_t w, uint32_t h);
 #ifdef USE_HWC2
     bool setAlpha(float alpha);
@@ -549,6 +557,10 @@
 
     void setParent(const sp<Layer>& layer);
 
+    LayerVector makeTraversalList();
+    void addZOrderRelative(const wp<Layer>& relative);
+    void removeZOrderRelative(const wp<Layer>& relative);
+
     // -----------------------------------------------------------------------
 
     class SyncPoint
diff --git a/services/surfaceflinger/LayerVector.cpp b/services/surfaceflinger/LayerVector.cpp
index 7ba6ad3..90e6395 100644
--- a/services/surfaceflinger/LayerVector.cpp
+++ b/services/surfaceflinger/LayerVector.cpp
@@ -42,13 +42,21 @@
 
 void LayerVector::traverseInZOrder(const std::function<void(Layer*)>& consume) const {
     for (size_t i = 0; i < size(); i++) {
-        (*this)[i]->traverseInZOrder(consume);
+        const auto& layer = (*this)[i];
+        if (layer->getDrawingState().zOrderRelativeOf != nullptr) {
+            continue;
+        }
+        layer->traverseInZOrder(consume);
     }
 }
 
 void LayerVector::traverseInReverseZOrder(const std::function<void(Layer*)>& consume) const {
     for (auto i = static_cast<int64_t>(size()) - 1; i >= 0; i--) {
-        (*this)[i]->traverseInReverseZOrder(consume);
+        const auto& layer = (*this)[i];
+        if (layer->getDrawingState().zOrderRelativeOf != nullptr) {
+            continue;
+        }
+        layer->traverseInReverseZOrder(consume);
      }
 }
 } // namespace android
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 26baaae..dcb24e4 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2820,6 +2820,11 @@
                 }
             }
         }
+        if (what & layer_state_t::eRelativeLayerChanged) {
+            if (layer->setRelativeLayer(s.relativeLayerHandle, s.z)) {
+                flags |= eTransactionNeeded|eTraversalNeeded;
+            }
+        }
         if (what & layer_state_t::eSizeChanged) {
             if (layer->setSize(s.w, s.h)) {
                 flags |= eTraversalNeeded;
diff --git a/services/surfaceflinger/tests/Transaction_test.cpp b/services/surfaceflinger/tests/Transaction_test.cpp
index a46ba48..441fc7e 100644
--- a/services/surfaceflinger/tests/Transaction_test.cpp
+++ b/services/surfaceflinger/tests/Transaction_test.cpp
@@ -662,6 +662,49 @@
     }
 }
 
+TEST_F(LayerUpdateTest, LayerSetRelativeLayerWorks) {
+    sp<ScreenCapture> sc;
+    {
+        SCOPED_TRACE("before adding relative surface");
+        ScreenCapture::captureScreen(&sc);
+        sc->expectBGColor(24, 24);
+        sc->expectFGColor(75, 75);
+        sc->expectBGColor(145, 145);
+    }
+
+    auto relativeSurfaceControl = mComposerClient->createSurface(
+            String8("Test Surface"), 64, 64, PIXEL_FORMAT_RGBA_8888, 0);
+    fillSurfaceRGBA8(relativeSurfaceControl, 255, 177, 177);
+    waitForPostedBuffers();
+
+    // Now we stack the surface above the foreground surface and make sure it is visible.
+    SurfaceComposerClient::openGlobalTransaction();
+    relativeSurfaceControl->setPosition(64, 64);
+    relativeSurfaceControl->show();
+    relativeSurfaceControl->setRelativeLayer(mFGSurfaceControl->getHandle(), 1);
+    SurfaceComposerClient::closeGlobalTransaction(true);
+
+
+    {
+        SCOPED_TRACE("after adding relative surface");
+        ScreenCapture::captureScreen(&sc);
+        // our relative surface should be visible now.
+        sc->checkPixel(75, 75, 255, 177, 177);
+    }
+
+    // A call to setLayer will override a call to setRelativeLayer
+    SurfaceComposerClient::openGlobalTransaction();
+    relativeSurfaceControl->setLayer(0);
+    SurfaceComposerClient::closeGlobalTransaction();
+
+    {
+        SCOPED_TRACE("after set layer");
+        ScreenCapture::captureScreen(&sc);
+        // now the FG surface should be visible again.
+        sc->expectFGColor(75, 75);
+    }
+}
+
 class ChildLayerTest : public LayerUpdateTest {
 protected:
     void SetUp() override {