diff --git a/guix/scripts/prefetch.scm b/guix/scripts/prefetch.scm
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@@ -0,0 +1,149 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2014 Nikita Karetnikov <address@hidden>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix 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 a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix scripts prefetch)
+  #:use-module (guix derivations)
+  #:use-module (guix packages)
+  #:use-module (guix store)
+  #:use-module (guix ui)
+  #:use-module (guix utils)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-37)
+  #:use-module (ice-9 match)
+  #:export (guix-prefetch))
+
+;;; Commentary:
+;;;
+;;; This program is used to download and add to the store all inputs that are
+;;; needed to build the specified packages.
+;;;
+;;; Code:
+
+(define (fold-values f acc seen lst)
+  (if (null-list? lst)
+      (values acc seen)
+      (let-values (((acc* seen*)
+                    (f acc seen (first lst))))
+        (fold-values f
+                     acc*
+                     seen*
+                     (cdr lst)))))
+
+(define (derivations-to-prefetch store drv)
+  "Return the list of fixed-output derivations that DRV depends on, directly
+or indirectly."
+  (define (unique-derivations acc seen lst)
+    ;; Return two values: the list of unique fixed-output derivations and the
+    ;; list of seen derivations.
+    (fold-values (lambda (acc seen drv-input)
+                   (let ((drv* (call-with-input-file (derivation-input-path drv-input)
+                                 read-derivation)))
+                     (cond ((fixed-output-derivation? drv*)
+                            (values (lset-adjoin equal? acc drv*)
+                                    seen))
+                           ((member drv* seen)
+                            (values acc seen))
+                           (else
+                            (unique-derivations acc
+                                                (cons drv* seen)
+                                                (derivation-inputs drv*))))))
+                 acc
+                 seen
+                 lst))
+
+  (identity  ; discard the second value
+   (unique-derivations '() '() (derivation-inputs drv))))
+
+
+;;;
+;;; Command-line options.
+;;;
+
+(define %default-options
+  '())
+
+(define (show-help)
+  (display (_ "Usage: guix prefetch [OPTION]... PACKAGES...
+Download and add to the store all inputs that are needed to build
+PACKAGES.\n"))
+  (display (_ "
+  -h, --help             display this help and exit"))
+  (display (_ "
+  -V, --version          display version information and exit"))
+  (newline)
+  (show-bug-report-information))
+
+(define %options
+  ;; Specification of the command-line options.
+  (list (option '(#\h "help") #f #f
+                 (lambda args
+                   (show-help)
+                   (exit 0)))
+        (option '(#\V "version") #f #f
+                (lambda args
+                  (show-version-and-exit "guix prefetch")))))
+
+
+;;;
+;;; Entry point.
+;;;
+
+;; XXX: remove me.
+(define specification->package+output
+  (@@ (guix scripts package) specification->package+output))
+
+(define (guix-prefetch . args)
+  (define (parse-options)
+    ;; Return the alist of option values.
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
+
+  (let ((opts  (parse-options))
+        (store (open-connection)))
+    (map (lambda (package)
+           (format #t "Prefetching the derivations for '~a':~%"
+                   (package-name package))
+
+           (build-derivations
+            store
+            (map (lambda (drv)
+                   ;; (format #t "   ~a~%" (derivation-file-name drv))
+                   (format #t "   ~a~%" drv)
+                   drv)
+                 (derivations-to-prefetch
+                  store
+                  (package-derivation store package)))))
+
+         (delete-duplicates
+          (filter-map (match-lambda
+                       (('argument . value)
+                        (identity  ; discard the second value
+                         ;; Check that all VALUEs in the list are valid
+                         ;; packages before calling 'derivations-to-prefetch'.
+                         ;; If VALUE is not a valid package,
+                         ;; 'specification->package+output' will raise an
+                         ;; error.
+                         (specification->package+output value)))
+                       (_ #f))
+                      (reverse opts))))))