diff --git a/indra/llrender/llvertexbuffer.cpp b/indra/llrender/llvertexbuffer.cpp
index 02160b09c4fcc21ca644fb2da60d182c791d9d7f..660dc14d0268d5d5b57b7a335f533e7318b2226c 100644
--- a/indra/llrender/llvertexbuffer.cpp
+++ b/indra/llrender/llvertexbuffer.cpp
@@ -47,6 +47,7 @@ U32 LLVertexBuffer::sSetCount = 0;
 S32 LLVertexBuffer::sCount = 0;
 S32 LLVertexBuffer::sGLCount = 0;
 S32 LLVertexBuffer::sMappedCount = 0;
+BOOL LLVertexBuffer::sDisableVBOMapping = FALSE ;
 BOOL LLVertexBuffer::sEnableVBOs = TRUE;
 U32 LLVertexBuffer::sGLRenderBuffer = 0;
 U32 LLVertexBuffer::sGLRenderIndices = 0;
@@ -212,6 +213,11 @@ void LLVertexBuffer::drawRange(U32 mode, U32 start, U32 end, U32 count, U32 indi
 {
 	llassert(mRequestedNumVerts >= 0);
 
+	if(mDirty)
+	{
+		postUpdate() ;
+	}
+
 	if (start >= (U32) mRequestedNumVerts ||
 	    end >= (U32) mRequestedNumVerts)
 	{
@@ -251,6 +257,12 @@ void LLVertexBuffer::drawRange(U32 mode, U32 start, U32 end, U32 count, U32 indi
 void LLVertexBuffer::draw(U32 mode, U32 count, U32 indices_offset) const
 {
 	llassert(mRequestedNumIndices >= 0);
+
+	if(mDirty)
+	{
+		postUpdate() ;
+	}
+
 	if (indices_offset >= (U32) mRequestedNumIndices ||
 	    indices_offset + count > (U32) mRequestedNumIndices)
 	{
@@ -282,6 +294,12 @@ void LLVertexBuffer::draw(U32 mode, U32 count, U32 indices_offset) const
 void LLVertexBuffer::drawArrays(U32 mode, U32 first, U32 count) const
 {
 	llassert(mRequestedNumVerts >= 0);
+
+	if(mDirty)
+	{
+		postUpdate() ;
+	}
+
 	if (first >= (U32) mRequestedNumVerts ||
 	    first + count > (U32) mRequestedNumVerts)
 	{
@@ -305,9 +323,10 @@ void LLVertexBuffer::drawArrays(U32 mode, U32 first, U32 count) const
 }
 
 //static
-void LLVertexBuffer::initClass(bool use_vbo)
+void LLVertexBuffer::initClass(bool use_vbo, bool no_vbo_mapping)
 {
 	sEnableVBOs = use_vbo;
+	sDisableVBOMapping = no_vbo_mapping ;
 	LLGLNamePool::registerPool(&sDynamicVBOPool);
 	LLGLNamePool::registerPool(&sDynamicIBOPool);
 	LLGLNamePool::registerPool(&sStreamVBOPool);
@@ -369,7 +388,8 @@ LLVertexBuffer::LLVertexBuffer(U32 typemask, S32 usage) :
 	mFilthy(FALSE),
 	mEmpty(TRUE),
 	mResized(FALSE),
-	mDynamicSize(FALSE)
+	mDynamicSize(FALSE),
+	mDirty(FALSE)
 {
 	LLMemType mt2(LLMemType::MTYPE_VERTEX_CONSTRUCTOR);
 	if (!sEnableVBOs)
@@ -567,6 +587,8 @@ void LLVertexBuffer::destroyGLBuffer()
 	{
 		if (useVBOs())
 		{
+			freeClientBuffer() ;
+
 			if (mMappedData || mMappedIndexData)
 			{
 				llerrs << "Vertex buffer destroyed while mapped!" << llendl;
@@ -594,11 +616,13 @@ void LLVertexBuffer::destroyGLIndices()
 	{
 		if (useVBOs())
 		{
+			freeClientBuffer() ;
+
 			if (mMappedData || mMappedIndexData)
 			{
 				llerrs << "Vertex buffer destroyed while mapped." << llendl;
 			}
-			releaseIndices();
+			releaseIndices();			
 		}
 		else
 		{
@@ -799,6 +823,7 @@ void LLVertexBuffer::resizeBuffer(S32 newnverts, S32 newnindices)
 
 	if (mResized && useVBOs())
 	{
+		freeClientBuffer() ;
 		setBuffer(0);
 	}
 }
@@ -822,6 +847,60 @@ BOOL LLVertexBuffer::useVBOs() const
 }
 
 //----------------------------------------------------------------------------
+void LLVertexBuffer::freeClientBuffer()
+{
+	if(useVBOs() && sDisableVBOMapping && (mMappedData || mMappedIndexData))
+	{
+		delete[] mMappedData ;
+		delete[] mMappedIndexData ;
+		mMappedData = NULL ;
+		mMappedIndexData = NULL ;
+	}
+}
+
+void LLVertexBuffer::preUpdate()
+{
+	if(!useVBOs() || !sDisableVBOMapping)
+	{
+		return ;
+	}
+
+	if(!mMappedData)
+	{
+		U32 size = getSize() ;
+		mMappedData = new U8[size];
+		memset(mMappedData, 0, size);
+	}
+
+	if(!mMappedIndexData)
+	{
+		U32 size = getIndicesSize();
+		mMappedIndexData = new U8[size];
+		memset(mMappedIndexData, 0, size);
+	}
+
+	mDirty = TRUE ;
+}
+
+void LLVertexBuffer::postUpdate() const
+{
+	if(!useVBOs() || !sDisableVBOMapping)
+	{
+		return ;
+	}
+
+	llassert_always(mMappedData && mMappedIndexData) ;
+
+	//release the existing buffers
+	glBufferDataARB(GL_ARRAY_BUFFER_ARB, 0, NULL, mUsage);
+	glBufferDataARB(GL_ELEMENT_ARRAY_BUFFER_ARB, 0, NULL, mUsage);
+
+	//update to the new buffers
+	glBufferDataARB(GL_ARRAY_BUFFER_ARB, getSize(), mMappedData, mUsage);
+	glBufferDataARB(GL_ELEMENT_ARRAY_BUFFER_ARB, getIndicesSize(), mMappedIndexData, mUsage);
+
+	mDirty = FALSE ;
+}
 
 // Map for data access
 U8* LLVertexBuffer::mapBuffer(S32 access)
@@ -836,6 +915,12 @@ U8* LLVertexBuffer::mapBuffer(S32 access)
 		llerrs << "LLVertexBuffer::mapBuffer() called on unallocated buffer." << llendl;
 	}
 		
+	if(useVBOs() && sDisableVBOMapping)
+	{
+		preUpdate() ;
+		return mMappedData ;
+	}
+
 	if (!mLocked && useVBOs())
 	{
 		{
@@ -906,7 +991,11 @@ void LLVertexBuffer::unmapBuffer()
 	LLMemType mt2(LLMemType::MTYPE_VERTEX_UNMAP_BUFFER);
 	if (mMappedData || mMappedIndexData)
 	{
-		if (useVBOs() && mLocked)
+		if(sDisableVBOMapping && useVBOs())
+		{
+			return ;
+		}
+		else if (useVBOs() && mLocked)
 		{
 			stop_glerror();
 			glUnmapBufferARB(GL_ARRAY_BUFFER_ARB);
@@ -1152,13 +1241,13 @@ void LLVertexBuffer::setBuffer(U32 data_mask)
 				}
 			}
 
-			if (mGLBuffer)
+			if (mGLBuffer && !sDisableVBOMapping)
 			{
 				stop_glerror();
 				glBufferDataARB(GL_ARRAY_BUFFER_ARB, getSize(), NULL, mUsage);
 				stop_glerror();
 			}
-			if (mGLIndices)
+			if (mGLIndices && !sDisableVBOMapping)
 			{
 				stop_glerror();
 				glBufferDataARB(GL_ELEMENT_ARRAY_BUFFER_ARB, getIndicesSize(), NULL, mUsage);
diff --git a/indra/llrender/llvertexbuffer.h b/indra/llrender/llvertexbuffer.h
index 94fa79095740b233365f8d45da12ee8e0f155ec1..18d50c87bb32ff56c2e31717c20b80e2710e0a55 100644
--- a/indra/llrender/llvertexbuffer.h
+++ b/indra/llrender/llvertexbuffer.h
@@ -80,7 +80,7 @@ class LLVertexBuffer : public LLRefCount
 
 	static BOOL	sUseStreamDraw;
 
-	static void initClass(bool use_vbo);
+	static void initClass(bool use_vbo, bool no_vbo_mapping);
 	static void cleanupClass();
 	static void setupClientArrays(U32 data_mask);
  	static void clientCopy(F64 max_time = 0.005); //copy data from client to GL
@@ -152,6 +152,11 @@ class LLVertexBuffer : public LLRefCount
 	void	allocateBuffer(S32 nverts, S32 nindices, bool create);
 	virtual void resizeBuffer(S32 newnverts, S32 newnindices);
 		
+	void preUpdate() ;
+	void postUpdate() const ;
+	void freeClientBuffer() ;
+	void dirty() {mDirty = TRUE;}
+
 	// Only call each getVertexPointer, etc, once before calling unmapBuffer()
 	// call unmapBuffer() after calls to getXXXStrider() before any cals to setBuffer()
 	// example:
@@ -216,6 +221,7 @@ class LLVertexBuffer : public LLRefCount
 	S32		mOffsets[TYPE_MAX];
 	BOOL	mResized;		// if TRUE, client buffer has been resized and GL buffer has not
 	BOOL	mDynamicSize;	// if TRUE, buffer has been resized at least once (and should be padded)
+	mutable BOOL    mDirty ;
 
 	class DirtyRegion
 	{
@@ -240,13 +246,14 @@ class LLVertexBuffer : public LLRefCount
 	static std::vector<U32> sDeleteList;
 	typedef std::list<LLVertexBuffer*> buffer_list_t;
 		
+	static BOOL sDisableVBOMapping; //disable glMapBufferARB
 	static BOOL sEnableVBOs;
+	static BOOL sVBOActive;
+	static BOOL sIBOActive;
 	static S32 sTypeOffsets[TYPE_MAX];
 	static U32 sGLMode[LLRender::NUM_MODES];
 	static U32 sGLRenderBuffer;
-	static U32 sGLRenderIndices;
-	static BOOL sVBOActive;
-	static BOOL sIBOActive;
+	static U32 sGLRenderIndices;	
 	static U32 sLastMask;
 	static U32 sAllocatedBytes;
 	static U32 sBindCount;
diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 6630d8f4003e3d83a96e66dfa5dbf3bf9802401a..58abd4c091d6472905785d253dd222a9d411dda2 100644
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -8451,6 +8451,17 @@
       <key>Value</key>
       <integer>1</integer>
     </map>
+    <key>RenderVBOMappingDisable</key>
+    <map>
+      <key>Comment</key>
+      <string>Disable VBO glMapBufferARB</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <integer>0</integer>
+    </map>
   <key>RenderUseStreamVBO</key>
   <map>
     <key>Comment</key>
diff --git a/indra/newview/llviewercontrol.cpp b/indra/newview/llviewercontrol.cpp
index 8c5a52c1878b3ba475d7761b4d96325a643711fc..3c53e54203c889196be62a0590a015bd3a512fcb 100644
--- a/indra/newview/llviewercontrol.cpp
+++ b/indra/newview/llviewercontrol.cpp
@@ -309,6 +309,15 @@ static bool handleRenderUseVBOChanged(const LLSD& newvalue)
 	return true;
 }
 
+static bool handleRenderUseVBOMappingChanged(const LLSD& newvalue)
+{
+	if (gPipeline.isInit())
+	{
+		gPipeline.setDisableVBOMapping(newvalue.asBoolean());
+	}
+	return true;
+}
+
 static bool handleWLSkyDetailChanged(const LLSD&)
 {
 	if (gSky.mVOWLSkyp.notNull())
@@ -589,6 +598,7 @@ void settings_setup_listeners()
 	gSavedSettings.getControl("MuteAmbient")->getSignal()->connect(boost::bind(&handleAudioVolumeChanged, _2));
 	gSavedSettings.getControl("MuteUI")->getSignal()->connect(boost::bind(&handleAudioVolumeChanged, _2));
 	gSavedSettings.getControl("RenderVBOEnable")->getSignal()->connect(boost::bind(&handleRenderUseVBOChanged, _2));
+	gSavedSettings.getControl("RenderVBOMappingDisable")->getSignal()->connect(boost::bind(&handleRenderUseVBOMappingChanged, _2));
 	gSavedSettings.getControl("RenderUseStreamVBO")->getSignal()->connect(boost::bind(&handleResetVertexBuffersChanged, _2));
 	gSavedSettings.getControl("WLSkyDetail")->getSignal()->connect(boost::bind(&handleWLSkyDetailChanged, _2));
 	gSavedSettings.getControl("NumpadControl")->getSignal()->connect(boost::bind(&handleNumpadControlChanged, _2));
diff --git a/indra/newview/llviewerwindow.cpp b/indra/newview/llviewerwindow.cpp
index 274dbe2cc8f1ca78a879c1d8d3bdfa945ad15c33..0028ced6c8aac6dca2312889ec5f9bc76d10e5dc 100644
--- a/indra/newview/llviewerwindow.cpp
+++ b/indra/newview/llviewerwindow.cpp
@@ -1477,7 +1477,7 @@ LLViewerWindow::LLViewerWindow(
 	{
 		gSavedSettings.setBOOL("RenderVBOEnable", FALSE);
 	}
-	LLVertexBuffer::initClass(gSavedSettings.getBOOL("RenderVBOEnable"));
+	LLVertexBuffer::initClass(gSavedSettings.getBOOL("RenderVBOEnable"), gSavedSettings.getBOOL("RenderVBOMappingDisable"));
 
 	if (LLFeatureManager::getInstance()->isSafe()
 		|| (gSavedSettings.getS32("LastFeatureVersion") != LLFeatureManager::getInstance()->getVersion())
diff --git a/indra/newview/pipeline.cpp b/indra/newview/pipeline.cpp
index 39bc35425074a54a173c23658a3f12dd8d5b9e86..13e537fae59a4935c44557008cc3a8fc47fdd4d4 100644
--- a/indra/newview/pipeline.cpp
+++ b/indra/newview/pipeline.cpp
@@ -5313,7 +5313,25 @@ void LLPipeline::setUseVBO(BOOL use_vbo)
 		}
 		
 		resetVertexBuffers();
-		LLVertexBuffer::initClass(use_vbo);
+		LLVertexBuffer::initClass(use_vbo, gSavedSettings.getBOOL("RenderVBOMappingDisable"));
+	}
+}
+
+void LLPipeline::setDisableVBOMapping(BOOL no_vbo_mapping)
+{
+	if (LLVertexBuffer::sEnableVBOs && no_vbo_mapping != LLVertexBuffer::sDisableVBOMapping)
+	{
+		if (no_vbo_mapping)
+		{
+			llinfos << "Disabling VBO glMapBufferARB." << llendl;
+		}
+		else
+		{ 
+			llinfos << "Enabling VBO glMapBufferARB." << llendl;
+		}
+		
+		resetVertexBuffers();
+		LLVertexBuffer::initClass(true, no_vbo_mapping);
 	}
 }
 
diff --git a/indra/newview/pipeline.h b/indra/newview/pipeline.h
index cef3d87f3605c84c554d51a09ad755d35a69e175..e99b0d71e3f632163e0d03be3dd6f663089ebe1a 100644
--- a/indra/newview/pipeline.h
+++ b/indra/newview/pipeline.h
@@ -111,6 +111,7 @@ class LLPipeline
 
 	void resetVertexBuffers(LLDrawable* drawable);
 	void setUseVBO(BOOL use_vbo);
+	void setDisableVBOMapping(BOOL no_vbo_mapping);
 	void generateImpostor(LLVOAvatar* avatar);
 	void bindScreenToTexture();
 	void renderBloom(BOOL for_snapshot, F32 zoom_factor = 1.f, int subfield = 0);