diff --git a/compat/regex/regcomp.c b/compat/regex/regcomp.c
index 29a71d31e444cb..53325f6468e9a6 100644
--- a/compat/regex/regcomp.c
+++ b/compat/regex/regcomp.c
@@ -2675,6 +2675,7 @@ build_range_exp (bitset_t sbcset, re_charset_t *mbcset, Idx *range_alloc,
 			    && strlen ((char *) end_elem->opr.name) > 1)))
     return REG_ECOLLATE;
 
+  {
   unsigned int
     start_ch = ((start_elem->type == SB_CHAR) ? start_elem->opr.ch
 		: ((start_elem->type == COLL_SYM) ? start_elem->opr.name[0]
@@ -2740,6 +2741,7 @@ build_range_exp (bitset_t sbcset, re_charset_t *mbcset, Idx *range_alloc,
       if (start_wc <= wc && wc <= end_wc)
 	bitset_set (sbcset, wc);
     }
+  }
 
   return REG_NOERROR;
 }
diff --git a/compat/regex/regex.c b/compat/regex/regex.c
index 1182dae6640426..191797fc43ea06 100644
--- a/compat/regex/regex.c
+++ b/compat/regex/regex.c
@@ -19,15 +19,33 @@
 
 #define __STDC_WANT_IEC_60559_BFP_EXT__
 
-#ifndef _LIBC
-# include <libc-config.h>
+#include <stdint.h>
+#include <stdbool.h>
 
-# if __GNUC_PREREQ (4, 6)
-#  pragma GCC diagnostic ignored "-Wsuggest-attribute=pure"
-#  pragma GCC diagnostic ignored "-Wvla"
-# endif
+#define __USE_GNU
+#define __STRICT_ANSI__
+#define assume(x)
+#define __glibc_unlikely(x) (x)
+#define __glibc_likely(x) (x)
+#define libc_hidden_def(name)
+#define weak_alias(name, aliasname)
+#define __always_inline inline
+#define nl_langinfo(x) "UTF8"
+#define FALLTHROUGH /* fallthru */
+#define uint_fast32_t uint32_t
+
+/* This imitates the `RESULT_MUST_BE_USED` macro in `git-compat-util.h` */
+/* The sentinel attribute is valid from gcc version 4.0 */
+#if defined(__GNUC__) && (__GNUC__ >= 4)
+/* warn_unused_result exists as of gcc 3.4.0, but be lazy and check 4.0 */
+#define __attribute_warn_unused_result__ __attribute__ ((warn_unused_result))
+#else
+#define __attribute_warn_unused_result__
 #endif
 
+/* True if the real type T is signed.  */
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+
 /* Make sure no one compiles this code with a C++ compiler.  */
 #if defined __cplusplus && defined _LIBC
 # error "This is C code, use a C compiler"
diff --git a/compat/regex/regex_internal.h b/compat/regex/regex_internal.h
index 345e895ced0543..9544183637eb05 100644
--- a/compat/regex/regex_internal.h
+++ b/compat/regex/regex_internal.h
@@ -24,19 +24,9 @@
 #include <stdio.h>
 #include <string.h>
 
-#include <langinfo.h>
 #include <locale.h>
 #include <wchar.h>
 #include <wctype.h>
-#include <stdckdint.h>
-#include <stdint.h>
-
-#ifndef _LIBC
-# include <dynarray.h>
-#endif
-
-#include <intprops.h>
-#include <verify.h>
 
 #if defined DEBUG && DEBUG != 0
 # include <assert.h>
@@ -818,14 +808,4 @@ re_string_elem_size_at (const re_string_t *pstr, Idx idx)
   return 1;
 }
 
-#ifdef _LIBC
-# if __glibc_has_attribute (__fallthrough__)
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# else
-#  define FALLTHROUGH ((void) 0)
-# endif
-#else
-# include "attribute.h"
-#endif
-
 #endif /*  _REGEX_INTERNAL_H */
diff --git a/compat/regex/regexec.c b/compat/regex/regexec.c
index 38ec76ebb60c35..0e461b6f226fe0 100644
--- a/compat/regex/regexec.c
+++ b/compat/regex/regexec.c
@@ -185,7 +185,7 @@ static reg_errcode_t extend_buffers (re_match_context_t *mctx, int min_len);
 
 int
 regexec (const regex_t *__restrict preg, const char *__restrict string,
-	 size_t nmatch, regmatch_t pmatch[_REGEX_NELTS (nmatch)], int eflags)
+	 size_t nmatch, regmatch_t *pmatch, int eflags)
 {
   reg_errcode_t err;
   Idx start, length;
@@ -1214,6 +1214,7 @@ proceed_next_node (const re_match_context_t *mctx, Idx nregs, regmatch_t *regs,
 	    return -2;
 	}
 
+      {
       /* Pick a valid destination, or return -1 if none is found.  */
       Idx dest_node = -1;
       for (Idx i = 0; i < edests->nelem; i++)
@@ -1242,6 +1243,7 @@ proceed_next_node (const re_match_context_t *mctx, Idx nregs, regmatch_t *regs,
 	    }
 	}
       return dest_node;
+      }
     }
   else
     {
@@ -1338,6 +1340,7 @@ pop_fail_stack (struct re_fail_stack_t *fs, Idx *pidx, Idx nregs,
 {
   if (fs == NULL || fs->num == 0)
     return -1;
+  {
   Idx num = --fs->num;
   *pidx = fs->stack[num].idx;
   memcpy (regs, fs->stack[num].regs, sizeof (regmatch_t) * nregs);
@@ -1347,13 +1350,13 @@ pop_fail_stack (struct re_fail_stack_t *fs, Idx *pidx, Idx nregs,
   *eps_via_nodes = fs->stack[num].eps_via_nodes;
   DEBUG_ASSERT (0 <= fs->stack[num].node);
   return fs->stack[num].node;
+  }
 }
 
 
 #define DYNARRAY_STRUCT  regmatch_list
 #define DYNARRAY_ELEMENT regmatch_t
 #define DYNARRAY_PREFIX  regmatch_list_
-#include <malloc/dynarray-skeleton.c>
 
 /* Set the positions where the subexpressions are starts/ends to registers
    PMATCH.