diff --git a/g10/gpg.c b/g10/gpg.c
index b759cc1cf..737753a40 100644
--- a/g10/gpg.c
+++ b/g10/gpg.c
@@ -68,6 +68,7 @@
 #include "../common/shareddefs.h"
 #include "../common/compliance.h"
 #include "../common/comopt.h"
+#include "../kbx/keybox.h"
 
 #if defined(HAVE_DOSISH_SYSTEM) || defined(__CYGWIN__)
 #define MY_O_BINARY  O_BINARY
@@ -447,6 +448,7 @@ enum cmd_and_opt_values
     oCompatibilityFlags,
     oAddDesigRevoker,
     oAssertSigner,
+    oKbxBufferSize,
 
     oNoop
   };
@@ -926,6 +928,7 @@ static gpgrt_opt_t opts[] = {
   /* Esoteric compatibility options.  */
   ARGPARSE_s_n (oRFC2440Text,      "rfc2440-text", "@"),
   ARGPARSE_s_n (oNoRFC2440Text, "no-rfc2440-text", "@"),
+  ARGPARSE_p_u (oKbxBufferSize,  "kbx-buffer-size", "@"),
 
   ARGPARSE_header (NULL, ""),  /* Stop the header group.  */
 
@@ -3743,6 +3746,9 @@ main (int argc, char **argv)
             add_to_strlist (&opt.assert_signer_list, pargs.r.ret_str);
 	    break;
 
+          case oKbxBufferSize:
+            keybox_set_buffersize (pargs.r.ret_ulong, 0);
+            break;
 
 	  case oNoop: break;
 
diff --git a/kbx/keybox-init.c b/kbx/keybox-init.c
index 0e37e3d9e..c83c4712f 100644
--- a/kbx/keybox-init.c
+++ b/kbx/keybox-init.c
@@ -28,8 +28,20 @@
 #include "../common/sysutils.h"
 #include "../common/mischelp.h"
 
+static unsigned int ll_buffer_size = 128;
+
 static KB_NAME kb_names;
 
+/* This object is used to mahe setvbuf buffers.  We use a short arary
+ * to be able to reuse already allocated buffers.  */
+struct stream_buffer_s
+{
+  int inuse;       /* True if used by a stream. */
+  size_t bufsize;
+  char *buf;
+};
+static struct stream_buffer_s stream_buffers[5];
+
 
 /* Register a filename for plain keybox files.  Returns 0 on success,
  * GPG_ERR_EEXIST if it has already been registered, or another error
@@ -85,6 +97,16 @@ keybox_is_writable (void *token)
 }
 
 
+/* Change the default buffering to KBYTES KiB; using 0 uses the syste
+ * buffers.  This function must be called early.  */
+void
+keybox_set_buffersize (unsigned int kbytes, int reserved)
+{
+  (void)reserved;
+  /* Round down to 8k multiples.  */
+  ll_buffer_size = (kbytes + 7)/8 * 8;
+}
+
 
 static KEYBOX_HANDLE
 do_keybox_new (KB_NAME resource, int secret, int for_openpgp)
@@ -248,6 +270,8 @@ gpg_error_t
 _keybox_ll_open (estream_t *rfp, const char *fname, unsigned int mode)
 {
   estream_t fp;
+  int i;
+  size_t bufsize;
 
   *rfp = NULL;
 
@@ -260,6 +284,37 @@ _keybox_ll_open (estream_t *rfp, const char *fname, unsigned int mode)
   if (!fp)
     return gpg_error_from_syserror ();
 
+  if (ll_buffer_size)
+    {
+      for (i=0; i < DIM (stream_buffers); i++)
+        if (!stream_buffers[i].inuse)
+          {
+            /* There is a free slot - we can use a larger buffer.  */
+            stream_buffers[i].inuse = 1;
+            if (!stream_buffers[i].buf)
+              {
+                bufsize = ll_buffer_size * 1024;
+                stream_buffers[i].buf = xtrymalloc (bufsize);
+                if (stream_buffers[i].buf)
+                  stream_buffers[i].bufsize = bufsize;
+                else
+                  {
+                    log_info ("can't allocate a large buffer for a kbx file;"
+                              " using default\n");
+                    stream_buffers[i].inuse = 0;
+                  }
+              }
+
+            if (stream_buffers[i].buf)
+              {
+                es_setvbuf (fp, stream_buffers[i].buf, _IOFBF,
+                            stream_buffers[i].bufsize);
+                es_opaque_set (fp, stream_buffers + i);
+              }
+            break;
+          }
+    }
+
   *rfp = fp;
   return 0;
 }
@@ -270,9 +325,29 @@ _keybox_ll_open (estream_t *rfp, const char *fname, unsigned int mode)
 gpg_error_t
 _keybox_ll_close (estream_t fp)
 {
-  if (fp && es_fclose (fp))
-    return gpg_error_from_syserror ();
-  return 0;
+  gpg_error_t err;
+  struct stream_buffer_s *sbuf;
+  int i;
+
+  if (!fp)
+    return 0;
+
+  sbuf = ll_buffer_size? es_opaque_get (fp) : NULL;
+  if (es_fclose (fp))
+    err = gpg_error_from_syserror ();
+  else
+    err = 0;
+  if (sbuf)
+    {
+      for (i=0; i < DIM (stream_buffers); i++)
+        if (stream_buffers + i == sbuf)
+          break;
+      log_assert (i < DIM (stream_buffers));
+      stream_buffers[i].inuse = 0;
+    }
+
+
+  return err;
 }
 
 
diff --git a/kbx/keybox.h b/kbx/keybox.h
index 9bff271ea..1146eca31 100644
--- a/kbx/keybox.h
+++ b/kbx/keybox.h
@@ -66,6 +66,7 @@ typedef enum
 /*-- keybox-init.c --*/
 gpg_error_t keybox_register_file (const char *fname, int secret,
                                   void **r_token);
+void keybox_set_buffersize (unsigned int kbytes, int reserved);
 int keybox_is_writable (void *token);
 
 KEYBOX_HANDLE keybox_new_openpgp (void *token, int secret);
diff --git a/sm/gpgsm.c b/sm/gpgsm.c
index aeb6ad7a9..55173f8a2 100644
--- a/sm/gpgsm.c
+++ b/sm/gpgsm.c
@@ -213,6 +213,7 @@ enum cmd_and_opt_values {
   oKeyboxdProgram,
   oRequireCompliance,
   oCompatibilityFlags,
+  oKbxBufferSize,
   oNoAutostart
  };
 
@@ -447,6 +448,7 @@ static gpgrt_opt_t opts[] = {
   ARGPARSE_s_s (oXauthority, "xauthority", "@"),
   ARGPARSE_s_s (oChUid, "chuid", "@"),
   ARGPARSE_s_s (oCompatibilityFlags, "compatibility-flags", "@"),
+  ARGPARSE_p_u (oKbxBufferSize,  "kbx-buffer-size", "@"),
 
   ARGPARSE_header (NULL, ""),  /* Stop the header group.  */
 
@@ -1492,6 +1494,10 @@ main ( int argc, char **argv)
 
         case oRequireCompliance: opt.require_compliance = 1;  break;
 
+        case oKbxBufferSize:
+          keybox_set_buffersize (pargs.r.ret_ulong, 0);
+          break;
+
         default:
           if (configname)
             pargs.err = ARGPARSE_PRINT_WARNING;