diff --git a/third_party/gmp/bootstrap.c b/third_party/gmp/bootstrap.c
new file mode 100644
index 0000000..5f8ed72
--- /dev/null
+++ b/third_party/gmp/bootstrap.c
@@ -0,0 +1,146 @@
+/* Functions needed for bootstrapping the gmp build, based on mini-gmp.
+
+Copyright 2001, 2002, 2004, 2011, 2012, 2015 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of either:
+
+  * the GNU Lesser General Public License as published by the Free
+    Software Foundation; either version 3 of the License, or (at your
+    option) any later version.
+
+or
+
+  * the GNU General Public License as published by the Free Software
+    Foundation; either version 2 of the License, or (at your option) any
+    later version.
+
+or both in parallel, as here.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library.  If not,
+see https://www.gnu.org/licenses/.  */
+
+
+#define MINI_GMP_DONT_USE_FLOAT_H 1
+#include "mini-gmp/mini-gmp.c"
+
+#define MIN(l,o) ((l) < (o) ? (l) : (o))
+#define PTR(x)   ((x)->_mp_d)
+#define SIZ(x)   ((x)->_mp_size)
+
+#define xmalloc gmp_default_alloc
+
+int
+isprime (unsigned long int t)
+{
+  unsigned long int q, r, d;
+
+  if (t < 32)
+    return (0xa08a28acUL >> t) & 1;
+  if ((t & 1) == 0)
+    return 0;
+
+  if (t % 3 == 0)
+    return 0;
+  if (t % 5 == 0)
+    return 0;
+  if (t % 7 == 0)
+    return 0;
+
+  for (d = 11;;)
+    {
+      q = t / d;
+      r = t - q * d;
+      if (q < d)
+	return 1;
+      if (r == 0)
+	break;
+      d += 2;
+      q = t / d;
+      r = t - q * d;
+      if (q < d)
+	return 1;
+      if (r == 0)
+	break;
+      d += 4;
+    }
+  return 0;
+}
+
+int
+log2_ceil (int n)
+{
+  int  e;
+  assert (n >= 1);
+  for (e = 0; ; e++)
+    if ((1 << e) >= n)
+      break;
+  return e;
+}
+
+/* Set inv to the inverse of d, in the style of invert_limb, ie. for
+   udiv_qrnnd_preinv.  */
+void
+mpz_preinv_invert (mpz_t inv, const mpz_t d, int numb_bits)
+{
+  mpz_t  t;
+  int    norm;
+  assert (SIZ(d) > 0);
+
+  norm = numb_bits - mpz_sizeinbase (d, 2);
+  assert (norm >= 0);
+  mpz_init (t);
+  mpz_setbit (t, 2*numb_bits - norm);
+  mpz_tdiv_q (inv, t, d);
+  mpz_clrbit (inv, numb_bits);
+
+  mpz_clear (t);
+}
+
+/* Calculate r satisfying r*d == 1 mod 2^n. */
+void
+mpz_invert_2exp (mpz_t r, const mpz_t a, unsigned long n)
+{
+  unsigned long  i;
+  mpz_t  inv, prod;
+
+  assert (mpz_odd_p (a));
+
+  mpz_init_set_ui (inv, 1L);
+  mpz_init (prod);
+
+  for (i = 1; i < n; i++)
+    {
+      mpz_mul (prod, inv, a);
+      if (mpz_tstbit (prod, i) != 0)
+	mpz_setbit (inv, i);
+    }
+
+  mpz_mul (prod, inv, a);
+  mpz_tdiv_r_2exp (prod, prod, n);
+  assert (mpz_cmp_ui (prod, 1L) == 0);
+
+  mpz_set (r, inv);
+
+  mpz_clear (inv);
+  mpz_clear (prod);
+}
+
+/* Calculate inv satisfying r*a == 1 mod 2^n. */
+void
+mpz_invert_ui_2exp (mpz_t r, unsigned long a, unsigned long n)
+{
+  mpz_t  az;
+
+  mpz_init_set_ui (az, a);
+  mpz_invert_2exp (r, az, n);
+  mpz_clear (az);
+}