diff --git a/pkgs/racket-doc/pkg/scribblings/pkg.scrbl b/pkgs/racket-doc/pkg/scribblings/pkg.scrbl
index 354bf9fc97..c580f061d3 100644
--- a/pkgs/racket-doc/pkg/scribblings/pkg.scrbl
+++ b/pkgs/racket-doc/pkg/scribblings/pkg.scrbl
@@ -285,8 +285,8 @@ is a GitHub package source.
 @margin-note{A Github repository source that starts with
 @litchar{git://} obtains the same content that would be accessed if
 @litchar{github.com} were not treated specially. The special treatment
-is preserved for historical reasons and because GitHub provides an
-interface that is always efficient.}
+is preserved for historical reasons, especially in combination
+with @envvar{PLT_USE_GITHUB_API}.}
 
 For backward compatibility, an older format is also supported:
 
@@ -304,7 +304,15 @@ with @litchar{git://github.com/} or @litchar{github://}; a package
 source that is otherwise specified as a GitHub reference is
 automatically prefixed with @litchar{git://github.com/}. The inferred
 package name is the last element of @nonterm{path} if it is non-empty,
-otherwise the inferred name is @nonterm{repo}.}
+otherwise the inferred name is @nonterm{repo}.
+
+If the @indexed-envvar{PLT_USE_GITHUB_API} environment variable is
+set, GitHub packages are obtained using the GitHub API protocol
+instead of using the Git protocol.
+
+@history[#:changed "6.2.900.16" @elem{Changed handling of
+                                      GitHub sources to use the Git
+                                      protocol by default.}]}
 
 @; ----------------------------------------
 @item{a @tech{package name} --- A @tech{package catalog} is
diff --git a/racket/collects/pkg/private/clone-path.rkt b/racket/collects/pkg/private/clone-path.rkt
index f7d79f7ee1..c6635fa9a6 100644
--- a/racket/collects/pkg/private/clone-path.rkt
+++ b/racket/collects/pkg/private/clone-path.rkt
@@ -372,9 +372,9 @@
            [else #f])]
          [(git github clone)
           (define pkg-url (string->url (pkg-desc-source d)))
-          (define-values (host port repo branch path)
-            (split-git-or-hub-url pkg-url))
-          (real-git-url pkg-url host port repo)]
+          (define-values (transport host port repo branch path)
+            (split-git-or-hub-url #:type type pkg-url))
+          (real-git-url pkg-url #:type type host port repo)]
          [else #f])))
 
 (define (pkg-info->clone-desc name info
diff --git a/racket/collects/pkg/private/download.rkt b/racket/collects/pkg/private/download.rkt
index 0fd31d07c1..93325312c2 100644
--- a/racket/collects/pkg/private/download.rkt
+++ b/racket/collects/pkg/private/download.rkt
@@ -98,7 +98,7 @@
                     #:log-debug-string (lambda (s) (log-pkg-debug s))))))
 
 
-(define (download-repo! url host port repo dest-dir checksum
+(define (download-repo! url transport host port repo dest-dir checksum
                         #:download-printf [download-printf #f]
                         #:use-cache? [use-cache? #t])
   (log-pkg-debug "\t\tDownloading ~a to ~a" (url->string url) dest-dir)
@@ -107,11 +107,16 @@
   (define unpacked? #f)
   
   (define (download!)
+    (when download-printf
+      (download-printf "Downloading repository ~a\n" (url->string url)))
     (git-checkout host #:port port repo
                   #:dest-dir dest-dir
                   #:ref checksum
-                  #:status-printf (or download-printf void)
-                  #:transport (string->symbol (url-scheme url)))
+                  #:status-printf (lambda (fmt . args)
+                                    (define (strip-ending-newline s)
+                                      (regexp-replace #rx"\n$" s ""))
+                                    (log-pkg-debug (strip-ending-newline (apply format fmt args))))
+                  #:transport transport)
     (set! unpacked? #t)
     ;; package directory as ".tgz" so it can be cached:
     (parameterize ([current-directory dest-dir])
diff --git a/racket/collects/pkg/private/orig-pkg.rkt b/racket/collects/pkg/private/orig-pkg.rkt
index 1c62ecc29c..4bd4d93906 100644
--- a/racket/collects/pkg/private/orig-pkg.rkt
+++ b/racket/collects/pkg/private/orig-pkg.rkt
@@ -22,7 +22,7 @@
                                                 (simple-form-path src)
                                                 #:more-than-root? #t)))]
     [(clone) 
-     (define-values (host port repo branch path)
+     (define-values (transport host port repo branch path)
        (split-git-or-hub-url (string->url src)))
      `(clone ,(path->string
                (find-relative-path (pkg-installed-dir)
diff --git a/racket/collects/pkg/private/repo-path.rkt b/racket/collects/pkg/private/repo-path.rkt
index acc9d91e46..a6589192c1 100644
--- a/racket/collects/pkg/private/repo-path.rkt
+++ b/racket/collects/pkg/private/repo-path.rkt
@@ -12,7 +12,10 @@
          split-git-url
          split-git-or-hub-url
          enclosing-path-for-repo
-         real-git-url)
+         real-git-url
+         use-git-for-github?)
+
+(define use-git-for-github? (not (getenv "PLT_USE_GITHUB_API")))
 
 (define (split-github-url pkg-url)
   (if (equal? (url-scheme pkg-url) "github")
@@ -32,7 +35,8 @@
 
 ;; returns: (values host repo branch path)
 (define (split-git-url pkg-url)
-  (values (url-host pkg-url)
+  (values (string->symbol (url-scheme pkg-url))
+          (url-host pkg-url)
           (url-port pkg-url)
           (string-join (map (compose ~a path/param-path)
                             (url-path/no-slash pkg-url))
@@ -40,15 +44,16 @@
           (or (url-fragment pkg-url) "master")
           (extract-git-path pkg-url)))
 
-(define (split-git-or-hub-url pkg-url)
-  (if (equal? "github" (url-scheme pkg-url))
+(define (split-git-or-hub-url pkg-url #:type [type #f])
+  (if (or (equal? "github" (url-scheme pkg-url))
+          (eq? type 'github))
       (match (split-github-url pkg-url)
         [(list* user repo branch path)
-         (values "github.com" #f (~a "/" user "/" repo) branch path)])
+         (values 'git "github.com" #f (~a user "/" repo) branch path)])
       (split-git-url pkg-url)))
 
 (define (enclosing-path-for-repo url-str in-repo-dir)
-  (define-values (host port repo branch path)
+  (define-values (transport host port repo branch path)
     (split-git-or-hub-url (string->url url-str)))
   (let loop ([path path]
              [in-repo-dir (simplify-path in-repo-dir)])
@@ -60,9 +65,10 @@
           (error "path for git repo link is too short for path in package source")
           (loop (cdr path) base))])))
 
-(define (real-git-url pkg-url host port repo)
+(define (real-git-url pkg-url host port repo #:type [type #f])
   (url->string
-   (if (equal? "github" (url-scheme pkg-url))
+   (if (or (equal? "github" (url-scheme pkg-url))
+           (eq? type 'github))
        ;; Convert "github://" to a real URL:
        (url "https" #f host port #t
             (map (lambda (s) (path/param s null)) (string-split repo "/"))
diff --git a/racket/collects/pkg/private/stage.rkt b/racket/collects/pkg/private/stage.rkt
index ca3ab5f24e..f62a5a578a 100644
--- a/racket/collects/pkg/private/stage.rkt
+++ b/racket/collects/pkg/private/stage.rkt
@@ -40,6 +40,12 @@
 
 (struct install-info (name orig-pkg directory git-directory clean? checksum module-paths additional-installs))
 
+(define (communication-type type)
+  (if (and (eq? type 'github)
+           use-git-for-github?)
+      'git
+      type))
+
 (define (remote-package-checksum pkg download-printf pkg-name
                                  #:type [type #f]
                                  #:catalog-lookup-cache [catalog-lookup-cache #f]
@@ -123,7 +129,7 @@
                         #:force-strip? force-strip?)]
    [(eq? type 'clone)
     (define pkg-url (string->url pkg))
-    (define-values (host port repo branch path)
+    (define-values (transport host port repo branch path)
       (split-git-or-hub-url pkg-url))
     (define pkg-no-query (real-git-url pkg-url host port repo))
     (define clone-dir (or given-at-dir
@@ -245,14 +251,15 @@
       (check-checksum given-checksum found-checksum "unexpected" pkg #f))
     (define checksum (or found-checksum given-checksum))
     (define downloaded-info
-       (match type
+       (match (communication-type type)
          ['git
           (when (equal? checksum "")
             (pkg-error 
              (~a "cannot use empty checksum for Git repostory package source\n"
                  "  source: ~a")
              pkg))
-          (define-values (host port repo branch path) (split-git-url pkg-url))
+          (define-values (transport host port repo branch path)
+            (split-git-or-hub-url pkg-url #:type type))
           (define tmp-dir
             (make-temporary-file
              (string-append
@@ -264,7 +271,7 @@
           (dynamic-wind
            void
            (λ ()
-             (download-repo! pkg-url host port repo tmp-dir checksum 
+             (download-repo! pkg-url transport host port repo tmp-dir checksum 
                              #:use-cache? use-cache?
                              #:download-printf download-printf)
              (lift-git-directory-content tmp-dir path)
@@ -696,10 +703,10 @@
                    (or given-type
                        (let-values ([(name type) (package-source->name+type pkg-url-str given-type)])
                          type))))
-  (case type
+  (case (communication-type type)
     [(git)
-     (define-values (host port repo branch path)
-       (split-git-url pkg-url))
+     (define-values (transport host port repo branch path)
+       (split-git-or-hub-url pkg-url #:type type))
      (download-printf "Querying Git references for ~a at ~a\n" pkg-name pkg-url-str)
      ;; Supplying `#:dest-dir #f` means that we just resolve `branch`
      ;; to an ID:
@@ -715,7 +722,7 @@
                                                     " the given URL might not refer to a Git repository\n"
                                                     "  given URL: ~a")
                                                 pkg-url-str))
-                   #:transport (string->symbol (url-scheme pkg-url)))]
+                   #:transport transport)]
     [(github)
      (match-define (list* user repo branch path)
                    (split-github-url pkg-url))