diff --git a/libcxx/docs/Makefile.sphinx b/libcxx/docs/Makefile.sphinx
deleted file mode 100644
--- a/libcxx/docs/Makefile.sphinx
+++ /dev/null
@@ -1,37 +0,0 @@
-# Makefile for Sphinx documentation
-#
-# FIXME: This hack is only in place to allow the libcxx.llvm.org/docs builder
-# to work with libcxx. This should be removed when that builder supports
-# out-of-tree builds.
-
-# You can set these variables from the command line.
-SPHINXOPTS    = -n -W -v
-SPHINXBUILD   = sphinx-build
-PAPER         =
-BUILDDIR      = _build
-
-# Internal variables.
-PAPEROPT_a4     = -D latex_paper_size=a4
-PAPEROPT_letter = -D latex_paper_size=letter
-ALLSPHINXOPTS   = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
-# the i18n builder cannot share the environment and doctrees with the others
-I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
-
-.PHONY: help clean html dirhtml singlehtml pickle json htmlhelp qthelp devhelp epub latex latexpdf text man changes linkcheck doctest gettext default
-
-default: html
-
-help:
-	@echo "Please use \`make <target>' where <target> is one of"
-	@echo "  html       to make standalone HTML files"
-
-clean:
-	-rm -rf $(BUILDDIR)/*
-
-html:
-	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
-	@echo
-	@# FIXME: Remove this `cp` once HTML->Sphinx transition is completed.
-	@# Kind of a hack, but HTML-formatted docs are on the way out anyway.
-	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
-
diff --git a/libcxx/docs/ReleaseNotes.rst b/libcxx/docs/ReleaseNotes.rst
--- a/libcxx/docs/ReleaseNotes.rst
+++ b/libcxx/docs/ReleaseNotes.rst
@@ -1,6 +1,6 @@
-=========================================
-Libc++ 14.0.0 (In-Progress) Release Notes
-=========================================
+==================================================
+Libc++ |version| |ReleaseNotesTitle|
+==================================================
 
 .. contents::
    :local:
@@ -8,17 +8,18 @@
 
 Written by the `Libc++ Team <https://libcxx.llvm.org>`_
 
-.. warning::
+.. only:: PreRelease
 
-   These are in-progress notes for the upcoming libc++ 14 release.
-   Release notes for previous releases can be found on
-   `the Download Page <https://releases.llvm.org/download.html>`_.
+  .. warning::
+     These are in-progress notes for the upcoming libc++ |version| release.
+     Release notes for previous releases can be found on
+     `the Download Page <https://releases.llvm.org/download.html>`_.
 
 Introduction
 ============
 
 This document contains the release notes for the libc++ C++ Standard Library,
-part of the LLVM Compiler Infrastructure, release 14.0.0. Here we describe the
+part of the LLVM Compiler Infrastructure, release |version|. Here we describe the
 status of libc++ in some detail, including major improvements from the previous
 release and new feature work. For the general LLVM release notes, see `the LLVM
 documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM releases may
@@ -32,8 +33,8 @@
 the current one. To see the release notes for a specific release, please
 see the `releases page <https://llvm.org/releases/>`_.
 
-What's New in Libc++ 14.0.0?
-============================
+What's New in Libc++ |version|?
+===============================
 
 New Features
 ------------
diff --git a/libcxx/docs/conf.py b/libcxx/docs/conf.py
--- a/libcxx/docs/conf.py
+++ b/libcxx/docs/conf.py
@@ -43,15 +43,6 @@
 project = u'libc++'
 copyright = u'2011-%d, LLVM Project' % date.today().year
 
-# The version info for the project you're documenting, acts as replacement for
-# |version| and |release|, also used in various other places throughout the
-# built documents.
-#
-# The short X.Y version.
-version = '14.0'
-# The full version, including alpha/beta/rc tags.
-release = '14.0'
-
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 #language = None
@@ -86,6 +77,11 @@
 # A list of ignored prefixes for module index sorting.
 #modindex_common_prefix = []
 
+in_progress_title = "(In-Progress) " if tags.has("PreRelease") else ""
+
+rst_epilog = f"""
+.. |ReleaseNotesTitle| replace:: {in_progress_title} Release Notes
+"""
 
 # -- Options for HTML output ---------------------------------------------------
 
diff --git a/llvm/cmake/modules/AddSphinxTarget.cmake b/llvm/cmake/modules/AddSphinxTarget.cmake
--- a/llvm/cmake/modules/AddSphinxTarget.cmake
+++ b/llvm/cmake/modules/AddSphinxTarget.cmake
@@ -38,6 +38,10 @@
     set(ARG_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
   endif()
 
+  if ("${LLVM_VERSION_SUFFIX}" STREQUAL "git")
+    set(PreReleaseTag "-tPreRelease")
+  endif()
+
   add_custom_target(${SPHINX_TARGET_NAME}
                     COMMAND ${CMAKE_COMMAND} -E env ${ARG_ENV_VARS}
                             ${SPHINX_EXECUTABLE}
@@ -45,6 +49,9 @@
                             -d "${SPHINX_DOC_TREE_DIR}"
                             -q # Quiet: no output other than errors and warnings.
                             -t builder-${builder} # tag for builder
+                            -D version=${LLVM_VERSION_MAJOR}
+                            -D release=${PACKAGE_VERSION}
+                            ${PreReleaseTag}
                             ${SPHINX_WARNINGS_AS_ERRORS_FLAG} # Treat warnings as errors if requested
                             "${ARG_SOURCE_DIR}" # Source
                             "${SPHINX_BUILD_DIR}" # Output