Index: release/scripts/startup/bl_ui/properties_data_modifier.py
===================================================================
--- release/scripts/startup/bl_ui/properties_data_modifier.py	(.../https://svn.blender.org/svnroot/bf-blender/trunk/blender)	(revision 50974)
+++ release/scripts/startup/bl_ui/properties_data_modifier.py	(working copy)
@@ -155,6 +155,7 @@
         col = split.column()
         col.prop(md, "frame_start")
         col.prop(md, "frame_duration")
+        col.prop(md, "reverse")
 
         col = split.column()
         col.prop(md, "use_random_order")
@@ -162,6 +163,8 @@
         sub.active = md.use_random_order
         sub.prop(md, "seed")
 
+	
+
     def CAST(self, layout, ob, md):
         split = layout.split(percentage=0.25)
 
Index: source/blender/modifiers/intern/MOD_build.c
===================================================================
--- source/blender/modifiers/intern/MOD_build.c	(.../https://svn.blender.org/svnroot/bf-blender/trunk/blender)	(revision 50974)
+++ source/blender/modifiers/intern/MOD_build.c	(working copy)
@@ -57,6 +57,7 @@
 
 	bmd->start = 1.0;
 	bmd->length = 100.0;
+	bmd->reverse = 1; // lucidlook@gmail.com
 }
 
 static void copyData(ModifierData *md, ModifierData *target)
@@ -68,6 +69,7 @@
 	tbmd->length = bmd->length;
 	tbmd->randomize = bmd->randomize;
 	tbmd->seed = bmd->seed;
+	tbmd->reverse = bmd->reverse;
 }
 
 static int dependsOnTime(ModifierData *UNUSED(md))
@@ -103,14 +105,25 @@
 	MEdge *medge_src = dm->getEdgeArray(dm);
 	MVert *mvert_src = dm->getVertArray(dm);
 
+      	if(bmd->reverse)  // lucidlook@gmail.com
+      	{
+		vertMap = MEM_callocN(sizeof(*vertMap) * numVert_src, "build modifier vertMap");
+		for (i = 0; i < numVert_src; i++) vertMap[i] = numVert_src - i;
+		edgeMap = MEM_callocN(sizeof(*edgeMap) * numEdge_src, "build modifier edgeMap");
+		for (i = 0; i < numEdge_src; i++) edgeMap[i] = numEdge_src - i;
+		faceMap = MEM_callocN(sizeof(*faceMap) * numPoly_src, "build modifier faceMap");
+		for (i = 0; i < numPoly_src; i++) faceMap[i] = numPoly_src - i;
+	}
+	else
+	{
+		vertMap = MEM_callocN(sizeof(*vertMap) * numVert_src, "build modifier vertMap");
+		for (i = 0; i < numVert_src; i++) vertMap[i] = i;
+		edgeMap = MEM_callocN(sizeof(*edgeMap) * numEdge_src, "build modifier edgeMap");
+		for (i = 0; i < numEdge_src; i++) edgeMap[i] = i;
+		faceMap = MEM_callocN(sizeof(*faceMap) * numPoly_src, "build modifier faceMap");
+		for (i = 0; i < numPoly_src; i++) faceMap[i] = i;
+	}
 
-	vertMap = MEM_callocN(sizeof(*vertMap) * numVert_src, "build modifier vertMap");
-	for (i = 0; i < numVert_src; i++) vertMap[i] = i;
-	edgeMap = MEM_callocN(sizeof(*edgeMap) * numEdge_src, "build modifier edgeMap");
-	for (i = 0; i < numEdge_src; i++) edgeMap[i] = i;
-	faceMap = MEM_callocN(sizeof(*faceMap) * numPoly_src, "build modifier faceMap");
-	for (i = 0; i < numPoly_src; i++) faceMap[i] = i;
-
 	frac = (BKE_scene_frame_get(md->scene) - bmd->start) / bmd->length;
 	CLAMP(frac, 0.0f, 1.0f);
 
Index: source/blender/makesdna/DNA_modifier_types.h
===================================================================
--- source/blender/makesdna/DNA_modifier_types.h	(.../https://svn.blender.org/svnroot/bf-blender/trunk/blender)	(revision 50974)
+++ source/blender/makesdna/DNA_modifier_types.h	(working copy)
@@ -161,7 +161,7 @@
 	ModifierData modifier;
 
 	float start, length;
-	int randomize, seed;
+	int randomize, seed, reverse; // lucidlook@gmail.com
 } BuildModifierData;
 
 /* Mask Modifier */
Index: source/blender/makesrna/intern/rna_modifier.c
===================================================================
--- source/blender/makesrna/intern/rna_modifier.c	(.../https://svn.blender.org/svnroot/bf-blender/trunk/blender)	(revision 50974)
+++ source/blender/makesrna/intern/rna_modifier.c	(working copy)
@@ -1052,6 +1052,12 @@
 	RNA_def_property_ui_text(prop, "Length", "Total time the build effect requires");
 	RNA_def_property_update(prop, 0, "rna_Modifier_update");
 
+	// lucidlook@gmail.com
+	prop = RNA_def_property(srna, "reverse", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "reverse", 1);
+	RNA_def_property_ui_text(prop, "Reverse", "Reverse the build sequence");
+	RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
 	prop = RNA_def_property(srna, "use_random_order", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "randomize", 1);
 	RNA_def_property_ui_text(prop, "Randomize", "Randomize the faces or edges during build");
@@ -1061,6 +1067,7 @@
 	RNA_def_property_range(prop, 1, MAXFRAMEF);
 	RNA_def_property_ui_text(prop, "Seed", "Seed for random if used");
 	RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
 }
 
 static void rna_def_modifier_mirror(BlenderRNA *brna)
Index: source/blender/blenloader/intern/readfile.c
===================================================================
--- source/blender/blenloader/intern/readfile.c	(.../https://svn.blender.org/svnroot/bf-blender/trunk/blender)	(revision 50974)
+++ source/blender/blenloader/intern/readfile.c	(working copy)
@@ -4587,6 +4587,7 @@
 			bmd->start = baf->sfra;
 			bmd->length = baf->len;
 			bmd->randomize = 0;
+			bmd->reverse = 0; // lucidlook@gmail.com
 			bmd->seed = 1;
 			
 			BLI_addtail(&ob->modifiers, bmd);