diff --git a/base/pkg.jl b/base/pkg.jl
index 3cf3872c669690..65312613b2e6e7 100644
--- a/base/pkg.jl
+++ b/base/pkg.jl
@@ -2,7 +2,7 @@
 
 module Pkg
 
-export Dir, GitHub, Types, Reqs, Cache, Read, Query, Resolve, Write, Generate, Entry
+export Dir, GitHub, Types, Reqs, Cache, Read, Query, Resolve, Write, Generate, Entry, Git
 export dir, init, rm, add, available, installed, status, clone, checkout,
        update, resolve, register, tag, publish, generate, test,
        build, free, pin, PkgError
@@ -14,7 +14,7 @@ type PkgError <: Exception
     msg::AbstractString
 end
 
-for file in split("dir github types reqs cache read query resolve write generate entry")
+for file in split("dir github types reqs cache read query resolve write generate entry git")
     include("pkg/$file.jl")
 end
 const cd = Dir.cd
diff --git a/base/pkg/git.jl b/base/pkg/git.jl
new file mode 100644
index 00000000000000..32e492f074dc1d
--- /dev/null
+++ b/base/pkg/git.jl
@@ -0,0 +1,124 @@
+# This file is a part of Julia. License is MIT: http://julialang.org/license
+
+module Git
+#
+# some utility functions for working with git repos
+#
+import Base: shell_escape
+
+function dir(d)
+    g = joinpath(d,".git")
+    isdir(g) && return g
+    normpath(d, Base.readchomp(setenv(`git rev-parse --git-dir`, dir=d)))
+end
+
+function git(d)
+    isempty(d) && return `git`
+    work_tree = abspath(d)
+    git_dir = joinpath(work_tree, dir(work_tree))
+    normpath(work_tree, ".") == normpath(git_dir, ".") ? # is it a bare repo?
+    `git --git-dir=$work_tree` : `git --work-tree=$work_tree --git-dir=$git_dir`
+end
+
+cmd(args::Cmd; dir="") = `$(git(dir)) $args`
+run(args::Cmd; dir="", out=STDOUT) = Base.run(pipeline(cmd(args,dir=dir), out))
+readall(args::Cmd; dir="") = Base.readall(cmd(args,dir=dir))
+readchomp(args::Cmd; dir="") = Base.readchomp(cmd(args,dir=dir))
+
+function success(args::Cmd; dir="")
+    g = git(dir)
+    Base.readchomp(`$g rev-parse --is-bare-repository`) == "false" &&
+        Base.run(`$g update-index -q --really-refresh`)
+    Base.success(`$g $args`)
+end
+
+function version()
+    vs = split(readchomp(`version`), ' ')[3]
+    ns = split(vs, '.')
+    if length(ns) > 3
+        VersionNumber(join(ns[1:3], '.'))
+    else
+        VersionNumber(join(ns, '.'))
+    end
+end
+
+modules(args::Cmd; dir="") = readchomp(`config -f .gitmodules $args`, dir=dir)
+different(verA::AbstractString, verB::AbstractString, path::AbstractString; dir="") =
+    !success(`diff-tree --quiet $verA $verB -- $path`, dir=dir)
+
+dirty(; dir="") = !success(`diff-index --quiet HEAD`, dir=dir)
+staged(; dir="") = !success(`diff-index --quiet --cached HEAD`, dir=dir)
+unstaged(; dir="") = !success(`diff-files --quiet`, dir=dir)
+dirty(paths; dir="") = !success(`diff-index --quiet HEAD -- $paths`, dir=dir)
+staged(paths; dir="") = !success(`diff-index --quiet --cached HEAD -- $paths`, dir=dir)
+unstaged(paths; dir="") = !success(`diff-files --quiet -- $paths`, dir=dir)
+
+iscommit(name; dir="") = success(`cat-file commit $name`, dir=dir)
+attached(; dir="") = success(`symbolic-ref -q HEAD`, dir=dir)
+branch(; dir="") = readchomp(`rev-parse --symbolic-full-name --abbrev-ref HEAD`, dir=dir)
+head(; dir="") = readchomp(`rev-parse HEAD`, dir=dir)
+
+function iscommit(sha1s::Vector; dir="")
+    indexin(sha1s,split(readchomp(`log --all --format=%H`, dir=dir),"\n")).!=0
+end
+
+immutable State
+    head::ASCIIString
+    index::ASCIIString
+    work::ASCIIString
+end
+
+function snapshot(; dir="")
+    head = readchomp(`rev-parse HEAD`, dir=dir)
+    index = readchomp(`write-tree`, dir=dir)
+    work = try
+        if length(readdir(abspath(dir))) > 1
+            run(`add --all`, dir=dir)
+            run(`add .`, dir=dir)
+        end
+        readchomp(`write-tree`, dir=dir)
+    finally
+        run(`read-tree $index`, dir=dir) # restore index
+    end
+    State(head, index, work)
+end
+
+function restore(s::State; dir="")
+    run(`reset -q --`, dir=dir)               # unstage everything
+    run(`read-tree $(s.work)`, dir=dir)       # move work tree to index
+    run(`checkout-index -fa`, dir=dir)        # check the index out to work
+    run(`clean -qdf`, dir=dir)                # remove everything else
+    run(`read-tree $(s.index)`, dir=dir)      # restore index
+    run(`reset -q --soft $(s.head)`, dir=dir) # restore head
+end
+
+function transact(f::Function; dir="")
+    state = snapshot(dir=dir)
+    try f() catch
+        restore(state, dir=dir)
+        rethrow()
+    end
+end
+
+function is_ancestor_of(a::AbstractString, b::AbstractString; dir="")
+    A = readchomp(`rev-parse $a`, dir=dir)
+    readchomp(`merge-base $A $b`, dir=dir) == A
+end
+
+const GITHUB_REGEX =
+    r"^(?:git@|git://|https://(?:[\w\.\+\-]+@)?)github.com[:/](([^/].+)/(.+?))(?:\.git)?$"i
+
+function set_remote_url(url::AbstractString; remote::AbstractString="origin", dir="")
+    run(`config remote.$remote.url $url`, dir=dir)
+    m = match(GITHUB_REGEX,url)
+    m === nothing && return
+    push = "git@github.com:$(m.captures[1]).git"
+    push != url && run(`config remote.$remote.pushurl $push`, dir=dir)
+end
+
+function normalize_url(url::AbstractString)
+    m = match(GITHUB_REGEX,url)
+    m === nothing ? url : "git://github.com/$(m.captures[1]).git"
+end
+
+end # module