diff --git a/testing/web-platform/tests/resources/chromium/webxr-test-math-helper.js b/testing/web-platform/tests/resources/chromium/webxr-test-math-helper.js
index 9f10a9d4b7f7..d47fde208dac 100644
--- a/testing/web-platform/tests/resources/chromium/webxr-test-math-helper.js
+++ b/testing/web-platform/tests/resources/chromium/webxr-test-math-helper.js
@@ -196,23 +196,23 @@ class XRMathHelper {
     const result2 = [
       // First column (m0r):
       invDet * det3x3(m11, m12, m13, m21, m22, m23, m32, m32, m33),
-      invDet * det3x3(m10, m12, m13, m20, m22, m23, m30, m32, m33),
+      -invDet * det3x3(m10, m12, m13, m20, m22, m23, m30, m32, m33),
       invDet * det3x3(m10, m11, m13, m20, m21, m23, m30, m31, m33),
-      invDet * det3x3(m10, m11, m12, m20, m21, m22, m30, m31, m32),
+      -invDet * det3x3(m10, m11, m12, m20, m21, m22, m30, m31, m32),
       // Second column (m1r):
-      invDet * det3x3(m01, m02, m03, m21, m22, m23, m32, m32, m33),
+      -invDet * det3x3(m01, m02, m03, m21, m22, m23, m32, m32, m33),
       invDet * det3x3(m00, m02, m03, m20, m22, m23, m30, m32, m33),
-      invDet * det3x3(m00, m01, m03, m20, m21, m23, m30, m31, m33),
+      -invDet * det3x3(m00, m01, m03, m20, m21, m23, m30, m31, m33),
       invDet * det3x3(m00, m01, m02, m20, m21, m22, m30, m31, m32),
       // Third column (m2r):
       invDet * det3x3(m01, m02, m03, m11, m12, m13, m31, m32, m33),
-      invDet * det3x3(m00, m02, m03, m10, m12, m13, m30, m32, m33),
+      -invDet * det3x3(m00, m02, m03, m10, m12, m13, m30, m32, m33),
       invDet * det3x3(m00, m01, m03, m10, m11, m13, m30, m31, m33),
-      invDet * det3x3(m00, m01, m02, m10, m11, m12, m30, m31, m32),
+      -invDet * det3x3(m00, m01, m02, m10, m11, m12, m30, m31, m32),
       // Fourth column (m3r):
-      invDet * det3x3(m01, m02, m03, m11, m12, m13, m21, m22, m23),
+      -invDet * det3x3(m01, m02, m03, m11, m12, m13, m21, m22, m23),
       invDet * det3x3(m00, m02, m03, m10, m12, m13, m20, m22, m23),
-      invDet * det3x3(m00, m01, m03, m10, m11, m13, m20, m21, m23),
+      -invDet * det3x3(m00, m01, m03, m10, m11, m13, m20, m21, m23),
       invDet * det3x3(m00, m01, m02, m10, m11, m12, m20, m21, m22),
     ];
 
diff --git a/testing/web-platform/tests/resources/chromium/webxr-test.js b/testing/web-platform/tests/resources/chromium/webxr-test.js
index a9dd9b1d7c7c..4401972c8b38 100644
--- a/testing/web-platform/tests/resources/chromium/webxr-test.js
+++ b/testing/web-platform/tests/resources/chromium/webxr-test.js
@@ -3,7 +3,7 @@
 // This polyfill library implements the WebXR Test API as specified here:
 // https://github.com/immersive-web/webxr-test-api
 
-
+// The standingTransform is floor_from_mojo and represented as such here.
 const default_standing = new gfx.mojom.Transform();
 default_standing.matrix = [1, 0, 0, 0,
                            0, 1, 0, 0,
@@ -409,8 +409,11 @@ class MockRuntime {
     }
 
     this.stageParameters_.standingTransform = new gfx.mojom.Transform();
+
+    // floorOrigin is passed in as mojoFromFloor; however, standingTransform is
+    // floorFromMojo so we need to invert the result of |getMatrixFromTransform|
     this.stageParameters_.standingTransform.matrix =
-      getMatrixFromTransform(floorOrigin);
+      XRMathHelper.inverse(getMatrixFromTransform(floorOrigin));
 
     this.onStageParametersUpdated();
   }
diff --git a/testing/web-platform/tests/webxr/hit-test/ar_hittest_subscription_refSpaces.https.html b/testing/web-platform/tests/webxr/hit-test/ar_hittest_subscription_refSpaces.https.html
index ecdfab479c7b..f1c223ae7495 100644
--- a/testing/web-platform/tests/webxr/hit-test/ar_hittest_subscription_refSpaces.https.html
+++ b/testing/web-platform/tests/webxr/hit-test/ar_hittest_subscription_refSpaces.https.html
@@ -17,14 +17,14 @@ const VIEWER_ORIGIN_TRANSFORM = {
 
 // 0.25m above world origin.
 const FLOOR_ORIGIN_TRANSFORM = {
-  position: [0, -0.25, 0],
+  position: [0, 0.25, 0],
   orientation: [0, 0, 0, 1],
 };
 
 const fakeDeviceInitParams = {
   supportedModes: ["immersive-ar"],
   views: VALID_VIEWS,
-  floorOrigin: FLOOR_ORIGIN_TRANSFORM,    // aka floor_from_mojo
+  floorOrigin: FLOOR_ORIGIN_TRANSFORM,    // aka mojo_from_floor
   viewerOrigin: VIEWER_ORIGIN_TRANSFORM,  // aka mojo_from_viewer
   supportedFeatures: ALL_FEATURES,
   world: createFakeWorld(5.0, 2.0, 5.0),  // webxr_test_constants_fake_world.js has detailed description of the fake world
diff --git a/testing/web-platform/tests/webxr/resources/webxr_test_constants.js b/testing/web-platform/tests/webxr/resources/webxr_test_constants.js
index 959859cba213..19ddbc24200d 100644
--- a/testing/web-platform/tests/webxr/resources/webxr_test_constants.js
+++ b/testing/web-platform/tests/webxr/resources/webxr_test_constants.js
@@ -71,7 +71,7 @@ const VALID_FLOOR_ORIGIN_MATRIX = [1, 0,    0,  0,
                                      1, 1.65, -1, 1];
 
 const VALID_FLOOR_ORIGIN = {
-    position: [1.0, 1.65, -1.0],
+    position: [-1.0, -1.65, 1.0],
     orientation: [0, 0, 0, 1]
 };
 
diff --git a/testing/web-platform/tests/webxr/xrReferenceSpace_originOffsetBounded.https.html b/testing/web-platform/tests/webxr/xrReferenceSpace_originOffsetBounded.https.html
index 7ef880c32c09..561c34ae9427 100644
--- a/testing/web-platform/tests/webxr/xrReferenceSpace_originOffsetBounded.https.html
+++ b/testing/web-platform/tests/webxr/xrReferenceSpace_originOffsetBounded.https.html
@@ -28,7 +28,7 @@ const VIEWS_WITH_OFFSET = [{
 }];
 
 const FLOOR_TRANSFORM = {
-  position: [0.1, 0.2, 0.3],
+  position: [-0.1, -0.2, -0.3],
   orientation: [0, 0, 0, 1]
 };
 
diff --git a/testing/web-platform/tests/webxr/xrReferenceSpace_relationships.https.html b/testing/web-platform/tests/webxr/xrReferenceSpace_relationships.https.html
new file mode 100644
index 000000000000..f97ca6639f7c
--- /dev/null
+++ b/testing/web-platform/tests/webxr/xrReferenceSpace_relationships.https.html
@@ -0,0 +1,59 @@
+
+<!DOCTYPE html>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<script src="resources/webxr_util.js"></script>
+<script src="resources/webxr_test_constants.js"></script>
+<script src="resources/webxr_test_asserts.js"></script>
+<canvas></canvas>
+<script>
+let testName =
+  "Bounded space, viewer space, local and local-floor space have correct poses w.r.t. each other";
+// 1m above world origin.
+const VIEWER_ORIGIN_TRANSFORM = {
+  position: [0, 1, 0],
+  orientation: [0, 0, 0, 1],
+};
+// 0.25m above world origin.
+const FLOOR_ORIGIN_TRANSFORM = {
+  position: [0, 0.25, 0],
+  orientation: [0, 0, 0, 1],
+};
+const fakeDeviceInitParams = {
+    supportsImmersive: true,
+    supportedModes: ["inline", "immersive-vr"],
+    views: VALID_VIEWS,
+    viewerOrigin: VIEWER_ORIGIN_TRANSFORM,
+    floorOrigin: FLOOR_ORIGIN_TRANSFORM,
+    supportedFeatures: ALL_FEATURES
+};
+let testFunction = function(session, fakeDeviceController, t) {
+  return new Promise((resolve, reject) => {
+    Promise.all([
+      session.requestReferenceSpace('bounded-floor'),
+      session.requestReferenceSpace('local'),
+      session.requestReferenceSpace('local-floor'),
+      session.requestReferenceSpace('viewer')
+    ]).then(([boundedSpace, localSpace, localFloorSpace, viewerSpace]) => {
+      t.step(() => {
+      });
+      const onFrame = function(time, xrFrame) {
+        const localFloorPoseInLocalSpace = xrFrame.getPose(localFloorSpace, localSpace);
+        const viewerPoseInLocalFloorSpace = xrFrame.getPose(viewerSpace, localFloorSpace);
+        const boundedFloorPoseInLocalFloorSpace = xrFrame.getPose(boundedSpace, localFloorSpace);
+        t.step(() => {
+          // Local floor space is supposed to be 0.25m above local space (aka world space).
+          assert_equals(localFloorPoseInLocalSpace.transform.position.y, 0.25);
+          // Bounded floor space should be at the same height as local floor space.
+          assert_equals(boundedFloorPoseInLocalFloorSpace.transform.position.y, 0.0);
+          // Viewer space should be additional 0.75m above local-floor space.
+          assert_equals(viewerPoseInLocalFloorSpace.transform.position.y, 0.75);
+        });
+        resolve();
+      }
+      session.requestAnimationFrame(onFrame);
+    });
+  });
+};
+xr_session_promise_test(testName, testFunction, fakeDeviceInitParams, 'immersive-vr', { 'requiredFeatures': ['local-floor', 'bounded-floor'] });
+</script>