diff --git a/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-struct-1.c b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-struct-1.c
new file mode 100644
index 00000000000..37862507870
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-struct-1.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-forwprop1-details -fdump-tree-optimized" } */
+/* PR tree-optimization/121841 */
+
+struct U2 {
+   int i[1024];
+};
+
+struct U2 g_284[1] = {{0UL}};
+struct U2 g_283[1];
+
+/* g_284[0] and g_283[0] are known not to
+   overlap so a copy prop can happen. */
+void func_1() {
+  struct U2 removeme;
+  removeme = g_284[0];
+  g_283[0] =  removeme;
+}
+
+/* { dg-final { scan-tree-dump-times "after previous" 1 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-not "removeme " "optimized" } } */
diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index f244b12b6d1..9c6f4b355d6 100644
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -1467,11 +1467,17 @@ optimize_agr_copyprop_1 (gimple *stmt, gimple *use_stmt,
       tree base1 = get_addr_base_and_unit_offset (dest2, &offset1);
       tree base2 = get_addr_base_and_unit_offset (src, &offset2);
       poly_int64 size = tree_to_poly_int64 (len);
+      /* If the bases are 2 different decls,
+	 then there can be no overlapping.  */
+      if (base1 && base2
+	  && DECL_P (base1) && DECL_P (base2)
+	  && base1 != base2)
+	;
       /* If we can't figure out the base or the bases are
 	 not equal then fall back to an alignment check.  */
-      if (!base1
-	  || !base2
-	  || !operand_equal_p (base1, base2))
+      else if (!base1
+	       || !base2
+	       || !operand_equal_p (base1, base2))
 	{
 	  unsigned int align1 = get_object_alignment (src);
 	  unsigned int align2 = get_object_alignment (dest2);