diff --git a/indra/newview/lldrawable.cpp b/indra/newview/lldrawable.cpp
index fec8b3c008..6d52c2ce56 100644
--- a/indra/newview/lldrawable.cpp
+++ b/indra/newview/lldrawable.cpp
@@ -1393,7 +1393,10 @@ void LLSpatialBridge::setVisible(LLCamera& camera_in, std::vector<LLDrawable*>*
 				LLVOAvatar* avatarp = (LLVOAvatar*) objparent;
 				if (avatarp->isVisible())
 				{
-					impostor = objparent->isAvatar() && ((LLVOAvatar*) objparent)->isImpostor();
+					// <FS:Ansariel> Fix LL impostor hacking
+					//impostor = objparent->isAvatar() && ((LLVOAvatar*) objparent)->isImpostor();
+					impostor = objparent->isAvatar() && avatarp->isImpostor() && !avatarp->needsImpostorUpdate();
+					// </FS:Ansariel>
 					loaded   = objparent->isAvatar() && ((LLVOAvatar*) objparent)->isFullyLoaded();
 				}
 				else
@@ -1483,7 +1486,10 @@ void LLSpatialBridge::updateDistance(LLCamera& camera_in, bool force_update)
 			if (parent && parent->getVObj())
 			{
 				LLVOAvatar* av = parent->getVObj()->asAvatar();
-				if (av && av->isImpostor())
+				// <FS:Ansariel> Fix LL impostor hacking
+				//if (av && av->isImpostor())
+				if (av && av->isImpostor() && !av->needsImpostorUpdate())
+				// </FS:Ansariel>
 				{
 					return;
 				}
diff --git a/indra/newview/lldrawpoolavatar.cpp b/indra/newview/lldrawpoolavatar.cpp
index 2de041629f..377faad4df 100644
--- a/indra/newview/lldrawpoolavatar.cpp
+++ b/indra/newview/lldrawpoolavatar.cpp
@@ -490,8 +490,11 @@ void LLDrawPoolAvatar::renderShadow(S32 pass)
 
 	BOOL impostor = avatarp->isImpostor();
 	if (impostor 
-		&& LLVOAvatar::AV_DO_NOT_RENDER != avatarp->getVisualMuteSettings()
-		&& LLVOAvatar::AV_ALWAYS_RENDER != avatarp->getVisualMuteSettings())
+		// <FS:Ansariel> Fix LL impostor hacking; No shadow for impostors
+		//&& LLVOAvatar::AV_DO_NOT_RENDER != avatarp->getVisualMuteSettings()
+		//&& LLVOAvatar::AV_ALWAYS_RENDER != avatarp->getVisualMuteSettings())
+		)
+		// </FS:Ansariel>
 	{
 		return;
 	}
@@ -1371,9 +1374,12 @@ void LLDrawPoolAvatar::renderAvatars(LLVOAvatar* single_avatar, S32 pass)
 
 	BOOL impostor = avatarp->isImpostor() && !single_avatar;
 
-	if (( /*avatarp->isInMuteList() // <FS:Ansariel> Partially undo MAINT-5700: Draw imposter for muted avatars
-		  ||*/ impostor 
-		  || (LLVOAvatar::AV_DO_NOT_RENDER == avatarp->getVisualMuteSettings() && !avatarp->needsImpostorUpdate()) ) && pass != 0)
+	// <FS:Ansariel> Fix LL impostor hacking; Don't render impostored avatars unless it needs an update
+	//if (( avatarp->isInMuteList()
+	//	  || impostor 
+	//	  || (LLVOAvatar::AV_DO_NOT_RENDER == avatarp->getVisualMuteSettings() && !avatarp->needsImpostorUpdate()) ) && pass != 0)
+	if (impostor && !avatarp->needsImpostorUpdate() && pass != 0)
+	// </FS:Ansariel>
 	{ //don't draw anything but the impostor for impostored avatars
 		return;
 	}
@@ -1390,7 +1396,10 @@ void LLDrawPoolAvatar::renderAvatars(LLVOAvatar* single_avatar, S32 pass)
 			LLVOAvatar::sNumVisibleAvatars++;
 		}
 
-		if (impostor || (LLVOAvatar::AV_DO_NOT_RENDER == avatarp->getVisualMuteSettings() && !avatarp->needsImpostorUpdate()))
+		// <FS:Ansariel> Fix LL impostor hacking
+		//if (impostor || (LLVOAvatar::AV_DO_NOT_RENDER == avatarp->getVisualMuteSettings() && !avatarp->needsImpostorUpdate()))
+		if (impostor && !avatarp->needsImpostorUpdate())
+		// </FS:Ansariel>
 		{
 			if (LLPipeline::sRenderDeferred && !LLPipeline::sReflectionRender && avatarp->mImpostor.isComplete()) 
 			{
diff --git a/indra/newview/llvoavatar.cpp b/indra/newview/llvoavatar.cpp
index 167c9c6625..7dd92684f4 100644
--- a/indra/newview/llvoavatar.cpp
+++ b/indra/newview/llvoavatar.cpp
@@ -2416,7 +2416,10 @@ void LLVOAvatar::idleUpdateMisc(bool detailed_update)
 	BOOL visible = isVisible() || mNeedsAnimUpdate;
 
 	// update attachments positions
-	if (detailed_update || !sUseImpostors)
+	// <FS:Ansariel> Fix LL impostor hacking; No detailed updates if muted when using no impostors
+	//if (detailed_update || !sUseImpostors)
+	if (detailed_update || (!sUseImpostors && !isInMuteList()))
+	// </FS:Ansariel>
 	{
 		LL_RECORD_BLOCK_TIME(FTM_ATTACHMENT_UPDATE);
 		for (attachment_map_t::iterator iter = mAttachmentPoints.begin(); 
@@ -3809,7 +3812,10 @@ BOOL LLVOAvatar::updateCharacter(LLAgent &agent)
 	//--------------------------------------------------------------------
 
 	bool visually_muted = isVisuallyMuted();
-	if (visible && (!isSelf() || visually_muted) && !mIsDummy && sUseImpostors && !mNeedsAnimUpdate && !sFreezeCounter)
+	// <FS:Ansariel> Fix LL impostor hacking; Adjust update period for muted avatars if using no impostors
+	//if (visible && (!isSelf() || visually_muted) && !mIsDummy && sUseImpostors && !mNeedsAnimUpdate && !sFreezeCounter)
+	if (visible && (!isSelf() || visually_muted) && !mIsDummy && (sUseImpostors || isInMuteList()) && !mNeedsAnimUpdate && !sFreezeCounter)
+	// </FS:Ansariel>
 	{
 		const LLVector4a* ext = mDrawable->getSpatialExtents();
 		LLVector4a size;
@@ -8988,7 +8994,10 @@ void LLVOAvatar::updateFreezeCounter(S32 counter)
 
 BOOL LLVOAvatar::updateLOD()
 {
-	if (isImpostor() && 0 != mDrawable->getNumFaces() && mDrawable->getFace(0)->hasGeometry())
+	// <FS:Ansariel> Fix LL impostor hacking
+	//if (isImpostor() && 0 != mDrawable->getNumFaces() && mDrawable->getFace(0)->hasGeometry())
+	if (isImpostor() && !needsImpostorUpdate() && 0 != mDrawable->getNumFaces() && mDrawable->getFace(0)->hasGeometry())
+	// </FS:Ansariel>
 	{
 		return TRUE;
 	}
@@ -9036,7 +9045,10 @@ void LLVOAvatar::updateImpostors()
 		LLVOAvatar* avatar = (LLVOAvatar*) *iter;
 		if (!avatar->isDead() && avatar->isVisible()
 			&& (
-                (avatar->isImpostor() || LLVOAvatar::AV_DO_NOT_RENDER == avatar->getVisualMuteSettings()) && avatar->needsImpostorUpdate())
+                // <FS:Ansariel> Fix LL impostor hacking; Generate new impostor if update is needed
+                //(avatar->isImpostor() || LLVOAvatar::AV_DO_NOT_RENDER == avatar->getVisualMuteSettings()) && avatar->needsImpostorUpdate())
+                avatar->isImpostor() && avatar->needsImpostorUpdate())
+                // </FS:Ansariel>
             )
 		{
             avatar->calcMutedAVColor();
@@ -9049,7 +9061,24 @@ void LLVOAvatar::updateImpostors()
 
 BOOL LLVOAvatar::isImpostor()
 {
-	return sUseImpostors && (isVisuallyMuted() || (mUpdatePeriod >= IMPOSTOR_PERIOD)) ? TRUE : FALSE;
+	// <FS:Ansariel> Fix LL impostor hacking
+	// IMPORTANT: LLPipeline::generateImpostor() will set sUseImporstors = FALSE when generating
+	//            an impostor. If checking for isImpostor() somewhere else to skip parts in the
+	//            rendering process, an additional check for needsImpostorUpdate() needs to be
+	//            done to determine if the particular part can really be skipped
+	//            (mNeedsImpostorUpdate = FALSE) or is currently needed to generate the
+	//            impostor (mNeedsImpostorUpdate = TRUE).
+
+	//return sUseImpostors && (isVisuallyMuted() || (mUpdatePeriod >= IMPOSTOR_PERIOD)) ? TRUE : FALSE;
+	if (sUseImpostors)
+	{
+		return (isVisuallyMuted() || (mUpdatePeriod >= IMPOSTOR_PERIOD));
+	}
+	else
+	{
+		return (LLVOAvatar::AV_DO_NOT_RENDER == getVisualMuteSettings() || isInMuteList());
+	}
+	// </FS:Ansariel>
 }
 
 BOOL LLVOAvatar::shouldImpostor(const U32 rank_factor) const
diff --git a/indra/newview/pipeline.cpp b/indra/newview/pipeline.cpp
index 483e4ed3bc..d26243191e 100644
--- a/indra/newview/pipeline.cpp
+++ b/indra/newview/pipeline.cpp
@@ -3194,9 +3194,12 @@ void LLPipeline::markVisible(LLDrawable *drawablep, LLCamera& camera)
 					if (vobj) // this test may not be needed, see above
 					{
 						LLVOAvatar* av = vobj->asAvatar();
-						if (av && (av->isImpostor() 
-							//|| av->isInMuteList() // <FS:Ansariel> Partially undo MAINT-5700: Draw imposter for muted avatars
-							|| (LLVOAvatar::AV_DO_NOT_RENDER == av->getVisualMuteSettings() && !av->needsImpostorUpdate()) ))
+						// <FS:Ansariel> Fix LL impostor hacking; Don't render impostored avatars unless it needs an update
+						//if (av && (av->isImpostor() 
+						//	|| av->isInMuteList()
+						//	|| (LLVOAvatar::AV_DO_NOT_RENDER == av->getVisualMuteSettings() && !av->needsImpostorUpdate()) ))
+						if (av && av->isImpostor() && !av->needsImpostorUpdate())
+						// </FS:Ansariel>
 						{
 							return;
 						}