diff --git a/doc/grep.in.1 b/doc/grep.in.1
index ecc8105..ea13964 100644
--- a/doc/grep.in.1
+++ b/doc/grep.in.1
@@ -472,6 +472,30 @@ or to set
 in the environment, in order to find more matches even if the matches
 are unsafe for direct display.
 .TP
+.BI \-p " COMMAND" "\fR,\fP \-\^\-preprocess=" COMMAND
+If this option is given, for each input file
+.I COMMAND
+is invoked with that input file as standard input and with grep reading
+and searching the standard output of
+.I COMMAND
+instead of direct file contents.  E.g., if
+.I COMMAND
+is
+.RB "\*(lq" "gzip -dc" "\*(rq"
+grep will decompress each file before searching it, assuming all
+inputs are gzipped.
+.I COMMAND
+is run via \fB${GREP_SHELL:-/bin/sh} -c COMMAND\fR.
+.IP
+The environment variable GREP_INPUT set to each input filename.
+This may be useful to dispatch to appropriate decoders.
+E.g., with a standard shell, (note single/double quoting),
+.nf
+  GPP='case "$GREP_INPUT" in *.gz) gzip -dc;; *) cat;; esac'
+.fi
+will allow \fB grep -p"$GPP"\fR to search through a mixture of
+gzipped and ordinary files.
+.TP
 .BI \-D " ACTION" "\fR,\fP \-\^\-devices=" ACTION
 If an input file is a device, FIFO or socket, use
 .I ACTION
diff --git a/src/grep.c b/src/grep.c
index bc47243..c629b13 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -21,6 +21,8 @@
 #include <config.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
+#include <string.h>
 #include <wchar.h>
 #include <fcntl.h>
 #include <inttypes.h>
@@ -415,7 +417,7 @@ static struct exclude *excluded_patterns[2];
 static struct exclude *excluded_directory_patterns[2];
 /* Short options.  */
 static char const short_options[] =
-"0123456789A:B:C:D:EFGHIPTUVX:abcd:e:f:hiLlm:noqRrsuvwxyZz";
+"0123456789A:B:C:D:EFGHIPTUVX:abcd:e:f:hiLlm:noqRrsuvwxyZzp:";
 
 /* Non-boolean long options that have no corresponding short equivalents.  */
 enum
@@ -484,6 +486,7 @@ static struct option const long_options[] =
   {"version", no_argument, NULL, 'V'},
   {"with-filename", no_argument, NULL, 'H'},
   {"word-regexp", no_argument, NULL, 'w'},
+  {"preprocess", required_argument, NULL, 'p'},
   {0, 0, 0, 0}
 };
 
@@ -535,6 +538,9 @@ static enum
     SKIP_DEVICES
   } devices = READ_COMMAND_LINE_DEVICES;
 
+static char *preproc;    /* if non-NULL pipe each file input to this command */
+static pid_t preprocPID; /* current preproc decoder child PID to wait for. */
+
 static bool grepfile (int, char const *, bool, bool);
 static bool grepdesc (int, bool);
 
@@ -1848,6 +1854,45 @@ grepdesc (int desc, bool command_line)
       goto closeout;
     }
 
+  if (preproc)            /* desc <- preprocessing decoder output */
+    {
+      int fds[2], ac = 0;
+      char *sh, *av[5 + 3];
+      if (pipe (fds) == -1)
+        die (EXIT_TROUBLE, 0, _("cannot create a pipe"));
+      switch (preprocPID = vfork ())
+        {
+        case 0:             /* child */
+          dup2 (desc, 0);   /* stdin = desc on file itself */
+          dup2 (fds[1], 1); /* stdout = write end of pipe [1] */
+          close (fds[1]);   /* do not need extra handle on pipe */
+          close (fds[0]);   /* close read end of pipe [0] */
+          setenv ("GREP_INPUT", filename, 1);
+          if (!(sh = getenv ("GREP_SHELL")))
+            sh = (char *)"/bin/sh";
+          /* build the argument vector for execvp */
+          ac = 0;
+          /* word-split GREP_SHELL a few times in case user needs option args */
+          av[ac] = strtok (sh, " \t");
+          for (ac++; ac < 5; ac++)
+            if (!(av[ac] = strtok (NULL, " \t")))
+              break;
+          /* append -c preproc */
+          av[ac++] = (char *) "-c";
+          av[ac++] = preproc;
+          av[ac] = NULL;
+          execvp (av[0], av); /* become a preprocessing decoder */
+          fprintf (stderr, "%s -c \"%s\": %s\n", sh, preproc, strerror (errno));
+          _exit (EXIT_TROUBLE);
+        default:            /* parent */
+          close (fds[1]);   /* close write end of pipe[1] */
+          close (desc);     /* close desc on file itself */
+          desc = fds[0];    /* replace desc value with read end of pipe [0] */
+          break;
+        case -1: /* vfork failed => resource exhaustion => die */
+          die (EXIT_TROUBLE, 0, _("cannot vfork"));
+        }
+    }
   count = grep (desc, &st, &ineof);
   if (count_matches)
     {
@@ -1876,6 +1921,21 @@ grepdesc (int desc, bool command_line)
         fflush_errno ();
     }
 
+  if (preprocPID)
+    {
+      int wstatus = 0;
+      /* Do not decode whole file if it won't be read anyway, e.g. -l mode. */
+      kill (preprocPID, SIGKILL); /* waitpid NOHANG before killing? */
+      while (waitpid (preprocPID, &wstatus, 0) == -1)
+        if (errno != EINTR)
+          break;
+      /* post-kill status always == success; Kid could fail sooner, though. */
+      if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != EXIT_SUCCESS)
+        die (EXIT_TROUBLE, 0, _("preprocess command failed"));
+      preprocPID = 0;
+      /*XXX verify that signal was SIGKILL and perhaps die otherwise? */
+    }
+
  closeout:
   if (desc != STDIN_FILENO && close (desc) != 0)
     suppressible_error (errno);
@@ -1958,6 +2018,7 @@ Output control:\n\
 "));
       printf (_("\
   -I                        equivalent to --binary-files=without-match\n\
+  -p, --preprocess=COMMAND  pipe file inputs to stdin of COMMAND pre-search\n\
   -d, --directories=ACTION  how to handle directories;\n\
                             ACTION is 'read', 'recurse', or 'skip'\n\
   -D, --devices=ACTION      how to handle devices, FIFOs and sockets;\n\
@@ -2678,6 +2739,10 @@ main (int argc, char **argv)
         eolbyte = '\0';
         break;
 
+      case 'p':
+        preproc = optarg;
+        break;
+
       case BINARY_FILES_OPTION:
         if (STREQ (optarg, "binary"))
           binary_files = BINARY_BINARY_FILES;