diff --git a/gcc/ipa-fnsummary.cc b/gcc/ipa-fnsummary.cc
index a6ccdb1852a..5ce4fb8bdc5 100644
--- a/gcc/ipa-fnsummary.cc
+++ b/gcc/ipa-fnsummary.cc
@@ -417,7 +417,11 @@ evaluate_conditions_for_known_args (struct cgraph_node *node,
 
 	  if (tree sval = avals->safe_sval_at (c->operand_num))
 	    val = ipa_find_agg_cst_from_init (sval, c->offset, c->by_ref);
-	  if (!val)
+	  /* ipa_argagg_value_list is indexed by byte offsets, so a condition
+	     which does not start at a byte boundary (a bit-field) cannot be
+	     looked up in it; the containing byte would be reinterpreted as
+	     the whole field below.  */
+	  if (!val && (c->offset % BITS_PER_UNIT) == 0)
 	    {
 	      ipa_argagg_value_list avs (avals);
 	      val = avs.get_value (c->operand_num, c->offset / BITS_PER_UNIT,
diff --git a/gcc/testsuite/gcc.dg/torture/pr126153.c b/gcc/testsuite/gcc.dg/torture/pr126153.c
new file mode 100644
index 00000000000..af37f47eef5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr126153.c
@@ -0,0 +1,52 @@
+/* { dg-do run { target le } } */
+/* { dg-require-effective-target int32plus } */
+/* { dg-options "-O2" } */
+
+/* Conditions of IPA predicates record the position of an aggregate load as
+   a bit offset, while the aggregate values of jump functions are indexed by
+   byte offsets.  Truncating the former used to match the constant recorded
+   for the byte containing the bit-field, which was then reinterpreted with
+   a VIEW_CONVERT_EXPR as if it were the whole field.  Here that turned the
+   value 1 of f7 into -4, the guard below into a false predicate and the
+   call to shifter() into __builtin_unreachable.  */
+
+struct S0 { unsigned f5 : 2; signed f7 : 3; unsigned f6 : 3; };
+struct S1 { int a; struct S0 f3; char pad; short s; };
+
+int g;
+
+__attribute__((noipa)) void ext (int x) { g += x; }
+
+__attribute__((noinline, noclone)) static long
+shifter (long l, int r)
+{
+  if (l < 0 || r < 0 || r >= 32 || l > (0x7fffffffffffffffL >> r))
+    return l;
+  return l << r;
+}
+
+static void
+callee (struct S1 p, int n)
+{
+  ext (n);
+  if ((int) p.f3.f7 >= 0)
+    ext ((int) shifter (0x350631DD6B880108LL, (int) p.f3.f7));
+  ext (n);
+}
+
+/* A second caller, so that callee is not inlined before IPA.  */
+void other (struct S1 q, int n) { callee (q, n); }
+
+int
+main (void)
+{
+  struct S1 l;
+  l.a = 5;
+  l.pad = 7;
+  l.s = 9;
+  *(char *) &l.f3 = 4;		/* f5 = 0, f7 = 1, f6 = 0 */
+  callee (l, 3);
+  if (g != 3 + 3 + (int) (0x350631DD6B880108LL << 1))
+    __builtin_abort ();
+  return 0;
+}