Introducing llvm-libtool-darwin

This diff starts the implementation of llvm-libtool-darwin
(an llvm based replacement of cctool's libtool).
Libtool is used for creating static and dynamic libraries
from a bunch of object files given as input.

Reviewed by alexshap, smeenai, jhenderson, MaskRay

Differential Revision: https://reviews.llvm.org/D82923
diff --git a/llvm/docs/CommandGuide/index.rst b/llvm/docs/CommandGuide/index.rst
index 77fece0..d13c2a0 100644
--- a/llvm/docs/CommandGuide/index.rst
+++ b/llvm/docs/CommandGuide/index.rst
@@ -14,25 +14,26 @@
 .. toctree::
    :maxdepth: 1
 
-   llvm-as
-   llvm-dis
-   opt
+   dsymutil
    llc
    lli
-   llvm-link
-   llvm-lib
-   llvm-lipo
+   llvm-as
    llvm-config
+   llvm-cov
    llvm-cxxmap
    llvm-diff
-   llvm-cov
+   llvm-dis
+   llvm-dwarfdump
+   llvm-lib
+   llvm-libtool-darwin
+   llvm-link
+   llvm-lipo
+   llvm-mca
    llvm-profdata
+   llvm-readobj
    llvm-stress
    llvm-symbolizer
-   llvm-dwarfdump
-   dsymutil
-   llvm-mca
-   llvm-readobj
+   opt
 
 GNU binutils replacements
 ~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/llvm/docs/CommandGuide/llvm-libtool-darwin.rst b/llvm/docs/CommandGuide/llvm-libtool-darwin.rst
new file mode 100644
index 0000000..0baacfd
--- /dev/null
+++ b/llvm/docs/CommandGuide/llvm-libtool-darwin.rst
@@ -0,0 +1,59 @@
+llvm-libtool-darwin - LLVM tool for creating libraries for Darwin
+=================================================================
+
+.. program:: llvm-libtool-darwin
+
+SYNOPSIS
+--------
+
+:program:`llvm-libtool-darwin` [*options*] *<input files>*
+
+DESCRIPTION
+-----------
+
+:program:`llvm-libtool-darwin` is a tool for creating static and dynamic
+libraries for Darwin.
+
+For most scenarios, it works as a drop-in replacement for cctools'
+:program:`libtool`.
+
+OPTIONS
+--------
+:program:`llvm-libtool-darwin` supports the following options:
+
+.. option:: -h, -help
+
+  Show help and usage for this command.
+
+.. option:: -help-list
+
+  Show help and usage for this command without grouping the options
+  into categories.
+
+.. option:: -color
+
+  Use colors in output.
+
+.. option:: -version
+
+  Display the version of this program.
+
+.. option:: -o <filename>
+
+  Specify the output file name. Must be specified exactly once.
+
+EXIT STATUS
+-----------
+
+:program:`llvm-libtool-darwin` exits with a non-zero exit code if there is an error.
+Otherwise, it exits with code 0.
+
+BUGS
+----
+
+To report bugs, please visit <https://bugs.llvm.org/>.
+
+SEE ALSO
+--------
+
+:manpage:`llvm-ar(1)`