diff --git a/OpenSim/Region/Framework/Scenes/Scene.cs b/OpenSim/Region/Framework/Scenes/Scene.cs
index 55c4fda45f..22969818fd 100755
--- a/OpenSim/Region/Framework/Scenes/Scene.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.cs
@@ -174,6 +174,13 @@ namespace OpenSim.Region.Framework.Scenes
 
         public SynchronizeSceneHandler SynchronizeScene;
 
+        public bool ClampNegativeZ
+        {
+            get { return m_clampNegativeZ; }
+        }
+
+        private bool m_clampNegativeZ = false;
+
         /// <summary>
         /// Used to prevent simultaneous calls to code that adds and removes agents.
         /// </summary>
@@ -1029,6 +1036,8 @@ namespace OpenSim.Region.Framework.Scenes
                     m_clampPrimSize = true;
                 }
 
+                m_clampNegativeZ = startupConfig.GetBoolean("ClampNegativeZ", m_clampNegativeZ);
+
                 m_useTrashOnDelete = startupConfig.GetBoolean("UseTrashOnDelete",m_useTrashOnDelete);
                 m_trustBinaries = startupConfig.GetBoolean("TrustBinaries", m_trustBinaries);
                 m_allowScriptCrossings = startupConfig.GetBoolean("AllowScriptCrossing", m_allowScriptCrossings);
diff --git a/OpenSim/Region/Framework/Scenes/SceneGraph.cs b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
index 930850091d..2ecb55b427 100755
--- a/OpenSim/Region/Framework/Scenes/SceneGraph.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
@@ -296,13 +296,15 @@ namespace OpenSim.Region.Framework.Scenes
                 Vector3 npos = new Vector3(sceneObject.RootPart.GroupPosition.X,
                                            sceneObject.RootPart.GroupPosition.Y,
                                            sceneObject.RootPart.GroupPosition.Z);
-                if (!(((sceneObject.RootPart.Shape.PCode == (byte)PCode.Prim) && (sceneObject.RootPart.Shape.State != 0))) && (npos.X < 0.0 || npos.Y < 0.0 || npos.Z < 0.0 ||
+                bool clampZ = m_parentScene.ClampNegativeZ;
+
+                if (!(((sceneObject.RootPart.Shape.PCode == (byte)PCode.Prim) && (sceneObject.RootPart.Shape.State != 0))) && (npos.X < 0.0 || npos.Y < 0.0 || (npos.Z < 0.0 && clampZ) ||
                     npos.X > regionSizeX ||
                     npos.Y > regionSizeY))
                 {
                     if (npos.X < 0.0) npos.X = 1.0f;
                     if (npos.Y < 0.0) npos.Y = 1.0f;
-                    if (npos.Z < 0.0) npos.Z = 0.0f;
+                    if (npos.Z < 0.0 && clampZ) npos.Z = 0.0f;
                     if (npos.X > regionSizeX) npos.X = regionSizeX - 1.0f;
                     if (npos.Y > regionSizeY) npos.Y = regionSizeY - 1.0f;
 
diff --git a/bin/OpenSimDefaults.ini b/bin/OpenSimDefaults.ini
index 09dda10409..72213537e2 100644
--- a/bin/OpenSimDefaults.ini
+++ b/bin/OpenSimDefaults.ini
@@ -138,6 +138,9 @@
     ; This can be overridden in the region config file.
     ClampPrimSize = false
 
+    ; If a prim is loaded from an external source, clamp it to Z = 0 if Z is negative.
+    ClampNegativeZ = false
+
     ; Maximum number of prims allowable in a linkset. Affects creating new linksets. Ignored if less than or equal to zero.
     ; This can be overridden in the region config file.
     LinksetPrims = 0