diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc
index ebd4e9864a1..8fb7a604591 100644
--- a/gcc/gimple-lower-bitint.cc
+++ b/gcc/gimple-lower-bitint.cc
@@ -77,7 +77,7 @@ enum bitint_prec_kind {
 
 static int small_max_prec, mid_min_prec, large_min_prec, huge_min_prec;
 static int limb_prec;
-static bool bitint_big_endian;
+static bool bitint_big_endian, bitint_extended;
 
 /* Categorize _BitInt(PREC) as small, middle, large or huge.  */
 
@@ -103,6 +103,7 @@ bitint_precision_kind (int prec)
       return bitint_prec_small;
     }
   bitint_big_endian = info.big_endian;
+  bitint_extended = info.extended;
   if (!large_min_prec
       && GET_MODE_PRECISION (limb_mode) < MAX_FIXED_MODE_SIZE)
     large_min_prec = MAX_FIXED_MODE_SIZE + 1;
@@ -3882,6 +3883,23 @@ bitint_large_huge::lower_shift_stmt (tree obj, gimple *stmt)
 	g = gimple_build_cond (GE_EXPR, add_cast (ssizetype, idx_next),
 			       ssize_int (0), NULL_TREE, NULL_TREE);
       insert_before (g);
+      if (bitint_extended && prec % limb_prec != 0)
+	{
+	  /* The most significant limb has been updated either in the
+	     loop or in the if after it.  To simplify the code, just
+	     read it back from memory and extend.  */
+	  m_gsi = gsi_after_labels (edge_false->dest);
+	  idx = bitint_big_endian ? size_zero_node : p;
+	  tree l = limb_access (TREE_TYPE (lhs), obj, idx, true);
+	  tree type = limb_access_type (TREE_TYPE (lhs), idx);
+	  tree v = make_ssa_name (m_limb_type);
+	  g = gimple_build_assign (v, l);
+	  insert_before (g);
+	  v = add_cast (type, v);
+	  l = limb_access (TREE_TYPE (lhs), obj, idx, true);
+	  g = gimple_build_assign (l, add_cast (m_limb_type, v));
+	  insert_before (g);
+	}
     }
 }
 
diff --git a/gcc/testsuite/gcc.dg/bitintext.h b/gcc/testsuite/gcc.dg/bitintext.h
new file mode 100644
index 00000000000..99fedb32a9a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitintext.h
@@ -0,0 +1,29 @@
+[[gnu::noipa]] void
+do_copy (void *p, const void *q, __SIZE_TYPE__ r)
+{
+  __builtin_memcpy (p, q, r);
+}
+
+/* Macro to test whether (on targets where psABI requires it) _BitInt
+   with padding bits have those filled with sign or zero extension.  */
+#if defined(__s390x__) || defined(__arm__) || defined(__loongarch__)
+#define BEXTC(x) \
+  do {								\
+    if ((typeof (x)) -1 < 0)					\
+      {								\
+	_BitInt(sizeof (x) * __CHAR_BIT__) __x;			\
+	do_copy (&__x, &(x), sizeof (__x));			\
+	if (__x != (x))						\
+	  __builtin_abort ();					\
+      }								\
+    else							\
+      {								\
+	unsigned _BitInt(sizeof (x) * __CHAR_BIT__) __x;	\
+	do_copy (&__x, &(x), sizeof (__x));			\
+	if (__x != (x))						\
+	  __builtin_abort ();					\
+      }								\
+  } while (0)
+#else
+#define BEXTC(x) do { (void) (x); } while (0)
+#endif
diff --git a/gcc/testsuite/gcc.dg/torture/bitint-82.c b/gcc/testsuite/gcc.dg/torture/bitint-82.c
new file mode 100644
index 00000000000..851d57a5598
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/bitint-82.c
@@ -0,0 +1,94 @@
+/* { dg-do run { target bitint } } */
+/* { dg-options "-std=c23 -pedantic-errors" } */
+/* { dg-skip-if "" { ! run_expensive_tests }  { "*" } { "-O0" "-O2" } } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
+
+#if __BITINT_MAXWIDTH__ >= 532
+_BitInt(5) a = 2, b = -2;
+_BitInt(38) c = 12345, d = -12345;
+_BitInt(129) e = 147090211948845388976606115811401318743wb, f = -147090211948845388976606115811401318743wb;
+_BitInt(532) g = 34476769918317100226195145251004381172591594205376273814wb, h = -102116935649428556311918486808926113041433456371844211259677321wb;
+unsigned _BitInt(1) i = 1;
+unsigned _BitInt(17) j = 49127uwb;
+unsigned _BitInt(60) k = 588141367522129848uwb;
+unsigned _BitInt(205) l = 33991671979236490040668305838261113909013362173682935296620088uwb;
+unsigned _BitInt(475) z = 14834685124553929878903720794923785539321715423294864257448721201977655202426343038777008759878862591302200019811097993772912691139803983786083uwb;
+#endif
+
+#include "../bitintext.h"
+
+#if __BITINT_MAXWIDTH__ >= 532
+[[gnu::noipa]] _BitInt(217)
+f1 (_BitInt(9) a, unsigned _BitInt(12) b, _BitInt(36) c, unsigned _BitInt(105) d,
+    _BitInt(135) e, unsigned _BitInt(168) f, _BitInt(207) g, _BitInt(207) h,
+    unsigned _BitInt(531) i, _BitInt(36) j)
+{
+  BEXTC (a); BEXTC (b); BEXTC (c); BEXTC (d);
+  BEXTC (e); BEXTC (f); BEXTC (g); BEXTC (h);
+  BEXTC (i); BEXTC (j);
+  _BitInt(9) k = a + 1;
+  unsigned _BitInt(12) l = b - a;
+  _BitInt(36) m = c * j;
+  unsigned _BitInt(105) n = d >> (-2 * j);
+  _BitInt(135) o = e | -j;
+  unsigned _BitInt(168) p = f & 101010101010101010101010uwb;
+  _BitInt(207) q = g * j;
+  _BitInt(207) r = g + h;
+  unsigned _BitInt(531) s = i / j;
+  BEXTC (k); BEXTC (l); BEXTC (m); BEXTC (n);
+  BEXTC (o); BEXTC (p); BEXTC (q); BEXTC (r);
+  BEXTC (s);
+  unsigned _BitInt(105) t = d << (38 - j);
+  BEXTC (t);
+  _Atomic _BitInt(5) u = 15;
+  u += 8U;
+  BEXTC (u);
+  _BitInt(135) v = e << 28;
+  BEXTC (v);
+  unsigned _BitInt(475) w = z << (29 + j);
+  BEXTC (w);
+  return a + 4;
+}
+#endif
+
+int
+main ()
+{
+#if __BITINT_MAXWIDTH__ >= 532
+  BEXTC (a); BEXTC (b);
+  BEXTC (c); BEXTC (d);
+  BEXTC (e); BEXTC (f);
+  BEXTC (g); BEXTC (h);
+  BEXTC (i);
+  BEXTC (j);
+  BEXTC (k);
+  BEXTC (l);
+  BEXTC (z);
+  {
+    _BitInt(5) a = 2, b = -2;
+    _BitInt(38) c = 12345, d = -12345;
+    _BitInt(129) e = 147090211948845388976606115811401318743wb, f = -147090211948845388976606115811401318743wb;
+    _BitInt(532) g = 34476769918317100226195145251004381172591594205376273814wb, h = -102116935649428556311918486808926113041433456371844211259677321wb;
+    unsigned _BitInt(1) i = 1;
+    unsigned _BitInt(17) j = 49127uwb;
+    unsigned _BitInt(60) k = 588141367522129848uwb;
+    unsigned _BitInt(205) l = 33991671979236490040668305838261113909013362173682935296620088uwb;
+    BEXTC (a); BEXTC (b);
+    BEXTC (c); BEXTC (d);
+    BEXTC (e); BEXTC (f);
+    BEXTC (g); BEXTC (h);
+    BEXTC (i);
+    BEXTC (j);
+    BEXTC (k);
+    BEXTC (l);
+  }
+  _BitInt(217) m = f1 (57wb, 3927uwb, 10625699364wb, 23030359755638571619326514462579uwb,
+		       20797625176303404170317957140841712396356wb,
+		       111831871006433449872067089878311637796827405335256uwb,
+		       64853652491049541618437564623858346454131583900201311683495230wb,
+		       25108562626494976011700565632680191924545340440636663075662700wb,
+		       6366583146545926097709747296452085257498446783797668089081516596003270602920229800152065594152964557479773813310423759077951305431130758723519892452009351743676uwb,
+		       -1);
+  BEXTC (m);
+#endif
+}