diff --git a/.hgtags b/.hgtags
index 2d66822e4d..8119300bc7 100755
--- a/.hgtags
+++ b/.hgtags
@@ -539,3 +539,4 @@ d07f76c5b9860fb87924d00ca729f7d4532534d6 3.7.29-release
 3f61ed662347dc7c6941b8266e72746a66d90e2a 3.8.1-release
 3a62616f3dd8bd512fcdfd29ef033b2505b11213 3.8.2-release
 60572f718879f786f6bc8b5c9373ebebf4693078 3.8.3-release
+27e3cf444c4cc645884960a61325a9ee0e9a2d0f 3.8.4-release
diff --git a/indra/newview/llfloatermodelpreview.cpp b/indra/newview/llfloatermodelpreview.cpp
index ca7f0b8a43..5afffbbb5f 100644
--- a/indra/newview/llfloatermodelpreview.cpp
+++ b/indra/newview/llfloatermodelpreview.cpp
@@ -209,6 +209,15 @@ LLViewerFetchedTexture* bindMaterialDiffuseTexture(const LLImportMaterial& mater
 	return NULL;
 }
 
+std::string stripSuffix(std::string name)
+{
+	if ((name.find("_LOD") != -1) || (name.find("_PHYS") != -1))
+	{
+		return name.substr(0, name.rfind('_'));
+	}
+	return name;
+}
+
 LLMeshFilePicker::LLMeshFilePicker(LLModelPreview* mp, S32 lod)
 // <FS:CR> Threaded Filepickers
 //: LLFilePickerThread(LLFilePicker::FFLOAD_COLLADA)
@@ -2048,6 +2057,83 @@ void LLModelPreview::loadModelCallback(S32 loaded_lod)
 			mBaseScene = mScene[loaded_lod];
 			mVertexBuffer[5].clear();
 		}
+		else
+		{
+			BOOL importerDebug = gSavedSettings.getBOOL("ImporterDebug");
+			BOOL legacyMatching = gSavedSettings.getBOOL("ImporterLegacyMatching");
+			if (!legacyMatching)
+			{
+				if (!mBaseModel.empty())
+				{ 
+					BOOL name_based = FALSE;
+					BOOL has_submodels = FALSE;
+					for (U32 idx = 0; idx < mBaseModel.size(); ++idx)
+					{
+						if (mBaseModel[idx]->mSubmodelID)
+						{ // don't do index-based renaming when the base model has submodels
+							has_submodels = TRUE;
+							if (importerDebug)
+							{
+								LL_INFOS() << "High LOD has submodels" << LL_ENDL;
+							}
+							break;
+						}
+					}
+
+					for (U32 idx = 0; idx < mModel[loaded_lod].size(); ++idx)
+					{
+						std::string loaded_name = stripSuffix(mModel[loaded_lod][idx]->mLabel);
+
+						LLModel* found_model = NULL;
+						LLMatrix4 transform;
+						FindModel(mBaseScene, loaded_name, found_model, transform);
+						if (found_model)
+						{ // don't rename correctly named models (even if they are placed in a wrong order)
+							name_based = TRUE;
+						}
+
+						if (mModel[loaded_lod][idx]->mSubmodelID)
+						{ // don't rename the models when loaded LOD model has submodels
+							has_submodels = TRUE;
+						}
+					}
+
+					if (importerDebug)
+					{
+						LL_INFOS() << "Loaded LOD " << loaded_lod << ": correct names" << (name_based ? "" : "NOT ") << "found; submodels " << (has_submodels ? "" : "NOT ") << "found" << LL_ENDL;
+					}
+
+					if (!name_based && !has_submodels)
+					{ // replace the name of the model loaded for any non-HIGH LOD to match the others (MAINT-5601)
+					  // this actually works like "ImporterLegacyMatching" for this particular LOD
+						for (U32 idx = 0; idx < mModel[loaded_lod].size() && idx < mBaseModel.size(); ++idx)
+						{ 
+							std::string name = mBaseModel[idx]->mLabel;
+							std::string loaded_name = stripSuffix(mModel[loaded_lod][idx]->mLabel);
+
+							if (loaded_name != name)
+							{
+								switch (loaded_lod)
+								{
+								case LLModel::LOD_IMPOSTOR: name += "_LOD0"; break;
+								case LLModel::LOD_LOW:      name += "_LOD1"; break;
+								case LLModel::LOD_MEDIUM:   name += "_LOD2"; break;
+								case LLModel::LOD_PHYSICS:  name += "_PHYS"; break;
+								case LLModel::LOD_HIGH:                      break;
+								}
+
+								if (importerDebug)
+								{
+									LL_WARNS() << "Loded model name " << mModel[loaded_lod][idx]->mLabel << " for LOD " << loaded_lod << " doesn't match the base model. Renaming to " << name << LL_ENDL;
+								}
+
+								mModel[loaded_lod][idx]->mLabel = name;
+							}
+						}
+					}
+				}
+			}
+		}
 
 		clearIncompatible(loaded_lod);
 
@@ -3854,7 +3940,7 @@ BOOL LLModelPreview::render()
 									genBuffers(LLModel::LOD_PHYSICS, false);
 								}
 
-								U32 num_models = mVertexBuffer[mPreviewLOD][model].size();
+								U32 num_models = mVertexBuffer[LLModel::LOD_PHYSICS][model].size();
 								for (U32 i = 0; i < num_models; ++i)
 								{
 									LLVertexBuffer* buffer = mVertexBuffer[LLModel::LOD_PHYSICS][model][i];