diff --git a/pxr/usdImaging/bin/testusdview/testenv/testUsdviewClippingPlanes/test.usda b/pxr/usdImaging/bin/testusdview/testenv/testUsdviewClippingPlanes/test.usda
index ddb808b5e1..c55a5141aa 100644
--- a/pxr/usdImaging/bin/testusdview/testenv/testUsdviewClippingPlanes/test.usda
+++ b/pxr/usdImaging/bin/testusdview/testenv/testUsdviewClippingPlanes/test.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "Implicits" (
     add variantSets = "shapeVariant"
diff --git a/pxr/usdImaging/bin/testusdview/testenv/testUsdviewDefaultMaterial/test.usda b/pxr/usdImaging/bin/testusdview/testenv/testUsdviewDefaultMaterial/test.usda
index ddb808b5e1..c55a5141aa 100644
--- a/pxr/usdImaging/bin/testusdview/testenv/testUsdviewDefaultMaterial/test.usda
+++ b/pxr/usdImaging/bin/testusdview/testenv/testUsdviewDefaultMaterial/test.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "Implicits" (
     add variantSets = "shapeVariant"
diff --git a/pxr/usdImaging/bin/testusdview/testenv/testUsdviewLights/test.usda b/pxr/usdImaging/bin/testusdview/testenv/testUsdviewLights/test.usda
index 02e049b3a1..3862d070de 100644
--- a/pxr/usdImaging/bin/testusdview/testenv/testUsdviewLights/test.usda
+++ b/pxr/usdImaging/bin/testusdview/testenv/testUsdviewLights/test.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "Implicits" (
     add variantSets = "shapeVariant"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLAnimatedLights/lightMoving.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLAnimatedLights/lightMoving.usda
index fd37789caa..b91160e0b8 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLAnimatedLights/lightMoving.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLAnimatedLights/lightMoving.usda
@@ -2,6 +2,7 @@
 (
     startTimeCode = 1
     endTimeCode = 3
+    upAxis = "Z"
 )
 
 def Sphere "sphere" {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/basicDrawing.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/basicDrawing.usda
index 5cc668c8ae..c33924643c 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/basicDrawing.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/basicDrawing.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 40
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Meshes"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/leftHanded.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/leftHanded.usda
index 75f613d90a..45e90c07ff 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/leftHanded.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/leftHanded.usda
@@ -3,6 +3,7 @@
     defaultPrim = "SimpleSphere"
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Mesh "SimpleSphere" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders-relative.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders-relative.usd
index a14a9680f3..5b22aa1b18 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders-relative.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders-relative.usd
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "Materials"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders.usd
index 4c26a21ba4..5d23baed06 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders.usd
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "Materials"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_anim.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_anim.usd
index 976245f657..f9f7046310 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_anim.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_anim.usd
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "Materials"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_bindings.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_bindings.usd
index a7754375fa..440efd6302 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_bindings.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/shaders_bindings.usd
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "Materials"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/textureChannels.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/textureChannels.usd
index 8cbd8ad8bf..61afaa4691 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/textureChannels.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/basicDrawing/textureChannels.usd
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 class Mesh "MeshProto"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/subdivTags.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/subdivTags.usda
index bfaff6abd3..d12bb10f9f 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/subdivTags.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawing/subdivTags.usda
@@ -1,4 +1,8 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
+
 
 def Xform "Geom"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders-relative.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders-relative.usd
index 17cd9e88ad..b5722bd1ce 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders-relative.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders-relative.usd
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "Materials"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usd
index 6f9c403cb7..dc916ef354 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usd
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "Materials"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usda
index 3da996d1d0..0b07c21c69 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicDrawingNonBindless/shaders.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "Looks"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicLighting/basicDrawing.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicLighting/basicDrawing.usda
index 5cc668c8ae..c33924643c 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicLighting/basicDrawing.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLBasicLighting/basicDrawing.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 40
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Meshes"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCards/testAnim.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCards/testAnim.usda
index 007de742a5..fbad0d8863 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCards/testAnim.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCards/testAnim.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 2
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "World" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLColorOpacityPrimvar/color_opacity_primvar.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLColorOpacityPrimvar/color_opacity_primvar.usda
index 0a898f2f28..aa4ed2241e 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLColorOpacityPrimvar/color_opacity_primvar.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLColorOpacityPrimvar/color_opacity_primvar.usda
@@ -2,6 +2,7 @@
 (
     endTimeCode = 1
     startTimeCode = 0
+    upAxis = "Z"
 )
 # Test the robust handling of color and opacity primvars in 
 # UsdImagingGprimAdapter.
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLComplexityOsd3/subdivMesh.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLComplexityOsd3/subdivMesh.usda
index eac2414f45..5919c1be63 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLComplexityOsd3/subdivMesh.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLComplexityOsd3/subdivMesh.usda
@@ -3,6 +3,7 @@
     doc = "Test Subdiv Tags"
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Mesh "pPlane1" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCurves/basicCurves.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCurves/basicCurves.usda
index 4d49de15fe..ca30c87880 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCurves/basicCurves.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLCurves/basicCurves.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 40
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Scope "World"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLDoubleSided/doubleSided2.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLDoubleSided/doubleSided2.usda
index 6330d2517d..b887760423 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLDoubleSided/doubleSided2.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLDoubleSided/doubleSided2.usda
@@ -3,6 +3,7 @@
     doc = "Test DoubleSided Imaging"
     endFrame = 40
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Meshes"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVarying.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVarying.usda
index fcfebeedef..8ef2a85430 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVarying.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVarying.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 class Mesh "QuadMeshProto"
 {
     point3f[] points = [
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLeftHanded.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLeftHanded.usda
index 868b93132a..859821c25d 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLeftHanded.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLeftHanded.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 class Mesh "QuadMeshProto"
 {
     int[] faceVertexCounts = [4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLinearInterp.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLinearInterp.usda
index 34e22776fe..afb52b5afa 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLinearInterp.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFaceVarying/testUsdImagingGLFaceVaryingLinearInterp.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 class Mesh "QuadMeshProto"
 {
     int[] faceVertexCounts = [4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFallbackPrimTypes/fallbacks3.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFallbackPrimTypes/fallbacks3.usda
index e305fdd268..86f2f8ed0d 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFallbackPrimTypes/fallbacks3.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFallbackPrimTypes/fallbacks3.usda
@@ -1,5 +1,6 @@
 #usda 1.0
 (
+    upAxis = "Z"
     subLayers = [@primitives.usda@]
     fallbackPrimTypes = {
         token[] UnknownCone = ["UnknownCylinder", "Cylinder"]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShading/primitives.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShading/primitives.usda
index 71b0ec2196..85892361be 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShading/primitives.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShading/primitives.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Capsule "MyCapsule"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShadingRef/primitives.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShadingRef/primitives.usda
index 71b0ec2196..85892361be 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShadingRef/primitives.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLFlatShadingRef/primitives.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Capsule "MyCapsule"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/instance.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/instance.usda
index 075dca581b..74639fd932 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/instance.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/instance.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "DormRoomDouble" (
     kind = "prop"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi.usda
index b012d138bc..e79294107c 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "World"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi_ni.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi_ni.usda
index ad63d516a5..9f1ad5a9ee 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi_ni.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHighlight/pi_ni.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "ProtoRed"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHoleFaces/holeFaces.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHoleFaces/holeFaces.usda
index cb6811c7ca..30fb869d9f 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHoleFaces/holeFaces.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLHoleFaces/holeFaces.usda
@@ -3,6 +3,7 @@
     doc = "Test Hole Imaging"
     endFrame = 40
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Mesh "pPlane1" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLImplicits/implicits.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLImplicits/implicits.usda
index 4bca053900..1cc9c1ed06 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLImplicits/implicits.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLImplicits/implicits.usda
@@ -3,6 +3,7 @@
     doc = "Implicit Geometry"
     endFrame = 20
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Fallback"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes.usd
index 6018360cb4..502c0e457e 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes.usd
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 class "_Depth_2"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Instanced.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Instanced.usd
index 490e47ff7b..bd273d801b 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Instanced.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Instanced.usd
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 class "_Depth_2"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Nested_Instances.usd b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Nested_Instances.usd
index a8aad807a4..55089e5120 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Nested_Instances.usd
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInheritedPurpose/InheritedPurposes_Nested_Instances.usd
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 class "_Depth_2"
 {
     custom token purpose = "proxy"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance.usda
index a52bb3abfc..73df86592f 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Parent" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance2.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance2.usda
index 0b3c43dc6b..c73c62c6a6 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance2.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance2.usda
@@ -11,6 +11,7 @@
     """
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Mesh" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance3.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance3.usda
index a28a0774cb..e5d81de2fa 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance3.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instance3.usda
@@ -11,6 +11,7 @@
     """
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Mesh" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes.usda
index 2ca9f0bf76..9c4c89a36a 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Cube"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2.usda
index 93ffd15f48..6d6de3a8db 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Cube"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2NoInstancing.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2NoInstancing.usda
index ff9b55d7b6..809f281777 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2NoInstancing.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/instancedCubes2NoInstancing.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Cube "Cube"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/nestedInstancedCubes.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/nestedInstancedCubes.usda
index a86e8a99be..628713e3cd 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/nestedInstancedCubes.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLInstancing/nestedInstancedCubes.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Cubes_1" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxDirectLights.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxDirectLights.usda
index 358eda0bf6..37ec29b0a2 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxDirectLights.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxDirectLights.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Sphere "mxSphere" {
     rel material:binding = </Materials/MaterialX/Materials/Default_White>
     color3f[] primvars:displayColor = [(0.1, 0.5, 0.8)]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGeomprop.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGeomprop.usda
index 5d94e47aea..7b622903a3 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGeomprop.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGeomprop.usda
@@ -1,5 +1,8 @@
 #usda 1.0
- 
+(
+    upAxis = "Z"
+)
+
 def Scope "MaterialX" (
     references = [
  		@./geomprop.mtlx@</MaterialX>,
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGlass.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGlass.usda
index f0aa7bf124..98f1b26166 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGlass.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxGlass.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Sphere "Default" {
     rel material:binding = </MaterialX/Materials/Default>
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Default.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Default.usda
index d3a1588bc1..8ac30cc670 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Default.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Default.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Scope "MaterialX_Default" {
     def Sphere "MxUsdDefault" {
         rel material:binding = </Materials/MaterialX/Materials/USD_Default>
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Gold.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Gold.usda
index d77cd8a074..7295651852 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Gold.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxPreviewSurfaceVsNative_Gold.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Scope "MaterialX_Gold" {
     def Sphere "MxUsdGold" {
         rel material:binding = </Materials/MaterialX/Materials/USD_Gold>
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxSimple.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxSimple.usda
index 4ff57f017a..0f28d26028 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxSimple.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxSimple.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Sphere "ball1" {
     rel material:binding = </Materials/MaterialX/Materials/Default_Smooth>
     color3f[] primvars:displayColor = [(0.1, 0.5, 0.8)]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured.usda
index 0b628e25b5..d500a85df7 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 
 def Mesh "UsdBrassSphere"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured2.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured2.usda
index 56bd2e177f..5485074e38 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured2.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/mxTextured2.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 
 def Mesh "TestSphere"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurface.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurface.usda
index b0ac843420..f520dd43de 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurface.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurface.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Sphere "ball1" {
     rel material:binding = </Materials/MaterialX/Materials/Car_Paint>
     color3f[] primvars:displayColor = [(0.1, 0.5, 0.8)]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurfaceMarble.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurfaceMarble.usda
index 7f31eb890d..dec913583c 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurfaceMarble.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/standardSurfaceMarble.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Sphere "ball1" {
     rel material:binding = </Materials/MaterialX/Materials/Emission>
     color3f[] primvars:displayColor = [(0.1, 0.5, 0.8)]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/usdPreviewSurface.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/usdPreviewSurface.usda
index 43b626f6fd..f1f66a719d 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/usdPreviewSurface.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMaterialX/usdPreviewSurface.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Sphere "ball1" {
     rel material:binding = </Materials/MaterialX/Materials/USD_Default_Green>
     color3f[] primvars:displayColor = [(0.1, 0.5, 0.8)]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMeshQuadrangulation/meshQuadrangulation.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMeshQuadrangulation/meshQuadrangulation.usda
index c2dd709cbf..db26a3c7fc 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMeshQuadrangulation/meshQuadrangulation.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMeshQuadrangulation/meshQuadrangulation.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 class "TestMesh"
 {
 #                 0--------4---18--7---24----9
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMipmap/testUsdImagingGLMipmap.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMipmap/testUsdImagingGLMipmap.usda
index 2d3d61c47b..64c99134ef 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMipmap/testUsdImagingGLMipmap.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLMipmap/testUsdImagingGLMipmap.usda
@@ -2,6 +2,7 @@
 (
     startTimeCode = 1
     endTimeCode = 19
+    upAxis = "Z"
 )
 
 def Material "Material"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLNormals/testNormals.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLNormals/testNormals.usda
index 09f4a35fbb..108590386d 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLNormals/testNormals.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLNormals/testNormals.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "R"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPickAndHighlight/instance.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPickAndHighlight/instance.usda
index 50d997aa84..1b83fefc7e 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPickAndHighlight/instance.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPickAndHighlight/instance.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Mesh "Plane1" (
     active = false
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/ni_pi.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/ni_pi.usda
index 94e90cca89..596875e6e1 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/ni_pi.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/ni_pi.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "World"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi.usda
index 570f9fa680..caa52f7e29 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "ProtoRed"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_basic.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_basic.usda
index faacf2a0e3..c8ab81baf0 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_basic.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_basic.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Root"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_masking.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_masking.usda
index a0202ccba8..81d6f89b64 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_masking.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_masking.usda
@@ -2,6 +2,7 @@
 (
     endTimeCode = 4
     startTimeCode = 0
+    upAxis = "Z"
 )
 
 def PointInstancer "Instancer" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni.usda
index ad63d516a5..9f1ad5a9ee 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "ProtoRed"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni2.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni2.usda
index f36c67fb4c..de49ee192e 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni2.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni2.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "ProtoRed"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material.usda
index af09f9c839..6224d98af5 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "ProtoRed"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material2.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material2.usda
index 43819de100..0d9d0b203d 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material2.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_material2.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "ProtoSphere"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_pi.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_pi.usda
index 199031acfc..da395cdfd6 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_pi.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_ni_pi.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def PointInstancer "ParentInstancer1"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi.usda
index 435d7de400..81ed0e3528 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "Cube"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi2.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi2.usda
index 2c3ed56489..193fef74ca 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi2.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi2.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "Cube"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_time.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_time.usda
index c5e2ce31af..f260228587 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_time.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_time.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 2
     startFrame = 0
+    upAxis = "Z"
 )
 
 def Xform "Root"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_varying.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_varying.usda
index 0169621dc5..98174c6a58 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_varying.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_pi_varying.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 24
     startFrame = 0
+    upAxis = "Z"
 )
 
 def PointInstancer "TopInstancer"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_root_prototype.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_root_prototype.usda
index 2dcb4f68c7..0182f77954 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_root_prototype.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_root_prototype.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Root"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_pi.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_pi.usda
index 1478b5b5b5..347a2e9de3 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_pi.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_pi.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Root"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_prototype.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_prototype.usda
index fc94eb2007..3fb1ef3dab 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_prototype.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_sibling_prototype.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 10
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Root"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_varying.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_varying.usda
index 531e5bb0e8..62d7c6a2e8 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_varying.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPointInstancer/pi_varying.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 30
     startFrame = 0
+    upAxis = "Z"
 )
 
 # ---------------------------------------------------------------------------- #
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPoints/basicPoints.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPoints/basicPoints.usda
index c9370bdbd8..ca2210f398 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPoints/basicPoints.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPoints/basicPoints.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 2
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Points "geo1" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceAnimated.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceAnimated.usda
index f73b0c822f..6d5e4ed3eb 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceAnimated.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceAnimated.usda
@@ -3,6 +3,7 @@
     defaultPrim = "Scene"
     endTimeCode = 4
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 def Xform "Scene" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceMaterialInterface.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceMaterialInterface.usda
index bc1a66089e..52f10cd6b3 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceMaterialInterface.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceMaterialInterface.usda
@@ -3,6 +3,7 @@
     defaultPrim = "Scene"
     endTimeCode = 1
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 def Xform "Scene" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceSourceColorSpace.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceSourceColorSpace.usda
index f971b1767a..bdc754fbf0 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceSourceColorSpace.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceSourceColorSpace.usda
@@ -3,6 +3,7 @@
     defaultPrim = "Scene"
     endTimeCode = 1
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 class Mesh "Plane" {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTexture.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTexture.usda
index b54834d498..745abd25a9 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTexture.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTexture.usda
@@ -3,6 +3,7 @@
     defaultPrim = "Scene"
     endTimeCode = 1
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 def Xform "Scene" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureOpacity.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureOpacity.usda
index 5db25d5a4d..548b3cea73 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureOpacity.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureOpacity.usda
@@ -3,6 +3,7 @@
     defaultPrim = "Scene"
     endTimeCode = 1
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 def Xform "Scene" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureScaleAndBias.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureScaleAndBias.usda
index bee081e5a8..65c45f0239 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureScaleAndBias.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTextureScaleAndBias.usda
@@ -3,6 +3,7 @@
     defaultPrim = "Scene"
     endTimeCode = 1
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 class Mesh "Plane" {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTransform2d.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTransform2d.usda
index b001a27135..bb1ec2575d 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTransform2d.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPreviewSurface/testPreviewSurfaceTransform2d.usda
@@ -3,6 +3,7 @@
     defaultPrim = "Scene"
     endTimeCode = 1
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 class Mesh "Plane" {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimitiveDrawingRef/primitives.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimitiveDrawingRef/primitives.usda
index 71b0ec2196..85892361be 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimitiveDrawingRef/primitives.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimitiveDrawingRef/primitives.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Capsule "MyCapsule"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarRefinement/testUsdImagingGLPrimvarRefinement.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarRefinement/testUsdImagingGLPrimvarRefinement.usda
index f83a8d8ec0..c6b768f909 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarRefinement/testUsdImagingGLPrimvarRefinement.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarRefinement/testUsdImagingGLPrimvarRefinement.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 class Mesh "QuadMeshProto"
 {
     point3f[] points = [
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing.usda
index acd8dbdf58..0f777afbe0 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing.usda
@@ -2,6 +2,7 @@
 (
     startTimeCode = 0
     endTimeCode = 2
+    upAxis = "Z"
 )
 
 def Xform "Geom"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing_colors.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing_colors.usda
index c74fc9d377..ad2e4a426f 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing_colors.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLPrimvarSharing/primvar_sharing_colors.usda
@@ -2,6 +2,7 @@
 (
     endTimeCode = 2
     startTimeCode = 0
+    upAxis = "Z"
 )
 
 def Xform "Geom"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/instancer.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/instancer.usda
index 338cdf12b1..93f8292ab4 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/instancer.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/instancer.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "Root"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/world.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/world.usda
index 1d42d8c8b6..d2509d4237 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/world.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLResync/world.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 def Scope "World" 
 {
    def "Model" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/object.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/object.usda
index 4b41925bd4..19c24c45f7 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/object.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/object.usda
@@ -1,5 +1,7 @@
 #usda 1.0
-
+(
+    upAxis = "Z"
+)
 def Xform "Geom"
 {
     def Mesh "Plane"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/usdGlslfxEmbedded.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/usdGlslfxEmbedded.usda
index 0e43797213..9f8f939125 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/usdGlslfxEmbedded.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSdr/usdGlslfxEmbedded.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "Geom"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeBadTexture/shader_change.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeBadTexture/shader_change.usda
index e1e5539c97..e3b2ec75a7 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeBadTexture/shader_change.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeBadTexture/shader_change.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 2
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Mesh "Mesh" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterial/coloredCubes.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterial/coloredCubes.usda
index 7ca73a368d..b27329ac97 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterial/coloredCubes.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterial/coloredCubes.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Cubes"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterialRef/coloredCubes.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterialRef/coloredCubes.usda
index 9704d7731e..b969a20e1f 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterialRef/coloredCubes.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLShadeMaterialRef/coloredCubes.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Cubes"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSkeleton/skeleton.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSkeleton/skeleton.usda
index 047271e37c..d1239dd48a 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSkeleton/skeleton.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSkeleton/skeleton.usda
@@ -2,6 +2,7 @@
 (
     endTimeCode = 3
     startTimeCode = 1
+    upAxis = "Z"
 )
 
 def SkelRoot "SkelChar"
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/lefthandedMesh.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/lefthandedMesh.usda
index 25890236bf..d05d95a5eb 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/lefthandedMesh.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/lefthandedMesh.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "xform"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/subdivMesh.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/subdivMesh.usda
index eac2414f45..5919c1be63 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/subdivMesh.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionOsd3/subdivMesh.usda
@@ -3,6 +3,7 @@
     doc = "Test Subdiv Tags"
     endFrame = 1
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Mesh "pPlane1" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionSchemeNone/ring.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionSchemeNone/ring.usda
index 1b3f239ddd..91d71389a5 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionSchemeNone/ring.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSubdivisionSchemeNone/ring.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Mesh "mesh"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSurfaceShader/shader_change.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSurfaceShader/shader_change.usda
index 8b9f3c270d..2b0f02c9a4 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSurfaceShader/shader_change.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLSurfaceShader/shader_change.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 2
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Mesh "Mesh" (
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLTriangleSubdivisionRuleOsd3/catmark_and_smooth_tris.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLTriangleSubdivisionRuleOsd3/catmark_and_smooth_tris.usda
index f58fbe973f..eb538a26d9 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLTriangleSubdivisionRuleOsd3/catmark_and_smooth_tris.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLTriangleSubdivisionRuleOsd3/catmark_and_smooth_tris.usda
@@ -1,8 +1,11 @@
 #usda 1.0
-# This test draws two identical cylindrical triangle meshes with catmullClark 
-# subdivision. The first uses catmullClark for the triangle weights, while 
-# the second uses smooth weights during subdivision.
-# The second cylinder should appear smoother.
+(
+    # This test draws two identical cylindrical triangle meshes with catmullClark
+    # subdivision. The first uses catmullClark for the triangle weights, while
+    # the second uses smooth weights during subdivision.
+    # The second cylinder should appear smoother.
+    upAxis = "Z"
+)
 def Mesh "catmark_smoothtris0"
 {
     int[] faceVertexCounts = [3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdLux/usdLux.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdLux/usdLux.usda
index b3ffeecaa7..fc37c024b1 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdLux/usdLux.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdLux/usdLux.usda
@@ -1,4 +1,7 @@
 #usda 1.0
+(
+    upAxis = "Z"
+)
 
 def Xform "transform"
 {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm.usda
index 56f8bba819..7e49b9b9c7 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm.usda
@@ -2,6 +2,7 @@
 (
     startTimeCode = 1
     endTimeCode = 10
+    upAxis = "Z"
 )
 def SkelRoot "Model" {
     def Skeleton "Skel" {
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm_baked.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm_baked.usda
index d0d0d67d7e..9f54da2b8b 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm_baked.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLUsdSkel/arm_baked.usda
@@ -3,6 +3,7 @@
     "Created by UsdView"
     endTimeCode = 10
     startTimeCode = 1
+    upAxis = "Z"
     subLayers = [
         @arm.usda@
     ]
diff --git a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLVaryingTopology/varying.usda b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLVaryingTopology/varying.usda
index effc8b5fca..6cf11eccb2 100644
--- a/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLVaryingTopology/varying.usda
+++ b/pxr/usdImaging/usdImagingGL/testenv/testUsdImagingGLVaryingTopology/varying.usda
@@ -2,6 +2,7 @@
 (
     endFrame = 3
     startFrame = 1
+    upAxis = "Z"
 )
 
 def Xform "Root" (