diff --git a/media/libvpx/vp8/encoder/block.h b/media/libvpx/vp8/encoder/block.h
--- a/media/libvpx/vp8/encoder/block.h
+++ b/media/libvpx/vp8/encoder/block.h
@@ -93,17 +93,18 @@ typedef struct macroblock
     int rddiv;
     int rdmult;
     unsigned int * mb_activity_ptr;
     int * mb_norm_activity_ptr;
     signed int act_zbin_adj;
     signed int last_act_zbin_adj;
 
     int *mvcost[2];
-    int *mvsadcost[2];
+    /* MSVC generates code that thinks this is 16-byte aligned */
+    DECLARE_ALIGNED(16, int*, mvsadcost[2]);
     int (*mbmode_cost)[MB_MODE_COUNT];
     int (*intra_uv_mode_cost)[MB_MODE_COUNT];
     int (*bmode_costs)[10][10];
     int *inter_bmode_costs;
     int (*token_costs)[COEF_BANDS][PREV_COEF_CONTEXTS]
     [MAX_ENTROPY_TOKENS];
 
     /* These define limits to motion vector components to prevent