diff --git a/Build.md b/Build.md
index 1a232a6..7ab1976 100644
--- a/Build.md
+++ b/Build.md
@@ -1,81 +1,179 @@
-* CMake 3.8 or higher
-* C++ Compiler with C++17 support:
-  * Clang 5 or higher
+Some distributions package a pre-built version of **ccls**.  See the
+system-specific sections below if you'd like to investigate that.
+
+Otherwise, you'll need to build **ccls** from source.  You will need:
+
+* The source code for **ccls**.
+* [CMake](https://cmake.org/) 3.8 or higher.
+* A C++ compiler with C++17 support:
+  * Clang 5 or higher.
   * GCC 7.2 or higher (`optional,string_view` require libstdc++7 or higher)
   * MSVC 2017 or higher (included with VS2017 Build Tools)
+* On GNU/Linux, either GNU make or Ninja (optional on other systems)
 
-See [[Getting-started]] for recommended configuration options for common systems.
+The simplest/quickest build with all defaults (only for POSIX systems) is:
 
-You may append `-G Ninja -DCMAKE_CXX_LINK_FLAGS=-fuse-ld=lld -DCMAKE_CXX_COMPILER=clang++`
+```sh
+git clone --depth=1 --recursive https://github.com/MaskRay/ccls
+cmake -H. -BRelease -DCMAKE_BUILD_TYPE=Release
+cmake --build Release
+```
+
+The resulting executable will be `Release/ccls`.
+
+See below for other CMake options available for customizing the build, hints
+for your system, as well as methods of obtaining and locating Clang+LLVM.
 
 ## CMake Options
 
+* `-G ('Unix Makefiles'|Ninja|Xcode|'Visual Studio 2017 x64')`
+
+  Choose a specific CMake generator (build tool).  Use `cmake --help` to see
+  your choices (not all options are available on all systems).  If not
+  specified CMake will choose an appropriate option for your system.
+
 * `-DCMAKE_BUILD_TYPE=(Debug|MinSizeRel|Release|RelWithDebInfo)`
 
-  Default: Release
-  Set the build type. The most important ones are Debug and Release.
+  Default: **Release**
+
+  Set the build type. The most important ones are **Debug** and **Release**.
+
+* `-DCMAKE_CXX_COMPILER=<compiler>`
+
+  Build **ccls** with the C++ compiler `<compiler>`.  If not specified CMake
+  will search for an appropriate C++ compiler.
+
+* `-DCMAKE_CXX_FLAGS=<flags>`
+
+  Use extra compiler flags `<flags>` when compiling **ccls**.  See the
+  system-specific sections below for some suggestions.
+
+* `-DCMAKE_INSTALL_PREFIX=<dir>`
+
+  Default: **/usr/local**
+
+  Set the install location.  See [[Install]] for more details.
+
+* `-DUSE_SHARED_LLVM=(ON|OFF)`
+
+  Default: **OFF**
+
+  Link against `libLLVM.so` instead of static LLVM libraries.  This makes
+  linking faster and the executable significantly smaller but the **ccls**
+  binary will need access to `libLLVM.so` at runtime as well as link-time.
+
+* `-DCLANG_USE_BUNDLED_LIBC++=(ON|OFF)`
+
+  Default: **OFF**
+
+  Clang provides libc++ libraries.  This option forces **ccls** to link with
+  these libraries.  This can be used on FreeBSD, but likely won't work on
+  Linux due to conflict of libstdc++ (linked by clang+llvm libraries) and
+  libc++.
+
+* `-DLLVM_ENABLE_RTTI=(ON|OFF)`
+
+  Default: **OFF**
+
+  Some system-supplied versions of `libLLVM` enable RTTI in which case
+  **ccls** must as well: use `-DLLVM_ENABLE_RTTI=ON`.  See the system-specific
+  sections below.
+
+## Choosing Clang+LLVM
+
+**ccls** requires `libLLVM` to implement its code parsing.  There are many
+ways it can be obtained.
 
 * `-DSYSTEM_CLANG=(ON|OFF)`
 
-  Default: OFF
-  Enable `SYSTEM_CLANG` if you want to link ccls against a system/local Clang instead of downloading Clang from releases.llvm.org during the configure process. You will probably need to install `libclang-*-dev` and `llvm-*-dev` packages (or equivalent) in order to have the correct libraries.
+  Default: **OFF**
 
-  ```zsh
-  % cmake -H. -BRelease -DCMAKE_INSTALL_PREFIX=/usr -DSYSTEM_CLANG=On
-  % cmake --build Release
-  ```
+  The default behavior of CMake is to download a pre-built binary of Clang.
+  If you prefer a different approach add `-DSYSTEM_CLANG=ON` and choose a
+  method below.
 
-  You can also use the option to use a downloaded and unpacked clang+llvm archive:
-  ```zsh
-  cmake -GNinja -H. -BBundled -DSYSTEM_CLANG=on -DCMAKE_PREFIX_PATH=$PWD/build/clang+llvm-7.0.0-x86_64-linux-gnu-ubuntu-14.04
-  ```
+### System Clang+LLVM
 
-  cmake will download the releases.llvm.org archive for you. If you want to download it manually:
-  ```zsh
-  rm -r Release
-  mkdir Release
-  cd Release
-  # download clang+llvm-6.0.1-x86_64-linux-gnu-ubuntu-16.04.tar.xz, verify with sha256sum and put it here
-  tar xf clang+llvm-6.0.1-x86_64-linux-gnu-ubuntu-16.04.tar.xz
-  cd ..
-  # cmake -H. -BRelease ...
-  ```
+If you want to link against a version of Clang+LLVM already installed on your
+system you will need to install `libclang-*-dev` and `llvm-*-dev` packages (or
+equivalent) in order to have the correct libraries.  If they are installed
+into the standard locations for our system, CMake will locate them.
 
-* `-DCMAKE_CXX_COMPILER=/usr/bin/clang++`
+```sh
+cmake -DSYSTEM_CLANG=ON
+```
 
-Build ccls with `/usr/bin/clang++`. You may use the absolute path of `Release/clang+llvm-*/bin/clang++` after clang+llvm archive is downloaded and extracted.
+### Alternate Clang+LLVM
 
-* `-DCLANG_USE_BUNDLED_LIBC++=on`
+If you wish to download and unpack Clang yourself rather than having CMake do
+it for you, or if you want to build Clang+LLVM from source, or if CMake can't
+find your installation of Clang+LLVM for any other reason, set the
+`CMAKE_PREFIX_PATH` CMake variable to point to the correct location:
 
-  `clang+llvm*` downloaded from releases.llvm.org also provides libc++ libraries.
-  This can be used on FreeBSD, but probably does not work on Linux due to conflict of libstdc++ (linked by clang+llvm libraries) and libc++.
+* `-DCMAKE_PREFIX_PATH=<clang-install-path>`
 
-  ```zsh
-  # If your clang++ is old, you may rerun this command with clang++ replaced to
-  # the absolute path of bundled/clang+llvm-*/bin/clang++
-  cmake -H. -Brelease -G Ninja -DCMAKE_CXX_COMPILER=clang++ -DCLANG_USE_BUNDLED_LIBC++=on
-  ```
+  CMake searches the paths in `CMAKE_PREFIX_PATH` for `include` and `lib`
+  subdirectories containing the required Clang headers and libraries.
 
-* `-DCMAKE_PREFIX_PATH="custom_install_path"`
+  You may add multiple directories for `include` and `lib` separated by a `;`,
+  e.g.: `-DCMAKE_PREFIX_PATH="$HOME/Dev/llvm/release;$HOME/Dev/llvm/tools/clang"`
 
-  When you want to use a system installed Clang but it is not installed into any
-  default CMake search location (for example if you built LLVM from source) you
-  can tell CMake where to search by adding search paths to `CMAKE_PREFIX_PATH`.
-  CMake searches the paths in `CMAKE_PREFIX_PATH` for 'include' and 'lib'
-  subdirectories containing the required Clang headers and libraries. For example,
-  to use a system installation of Clang on Windows you can add the following
-  option: `-DCMAKE_PREFIX_PATH="C:/Program Files/LLVM"`.
+## GNU/Linux
 
-  You may add directories for `include` and `lib` separated by a `;`, e.g. to use trunk clang:
-  `-DCMAKE_PREFIX_PATH="$HOME/Dev/llvm/release;$HOME/Dev/llvm/tools/clang"`
+* On GNU/Linux distributions with older versions of glibc (older than
+  2013-04-25), such as Red Hat EL 6.x, you may need to add the `-D__STDC_FORMAT_MACROS` option to `CMAKE_CXX_FLAGS`:
 
-* `-DUSE_SHARED_LLVM=on`
+  `-DCMAKE_CXX_FLAGS=-D__STDC_FORMAT_MACROS`
 
-  Link against `libLLVM.so` instead of `libLLVMSupport.a libLLVMDemangle.a ...` This makes linking faster and the executable significantly smaller.
+### Arch Linux
+
+To install pre-built **ccls**, use
+[aur/ccls-git](https://aur.archlinux.org/packages/ccls-git).
+
+To build **ccls** on Arch Linux with system Clang+LLVM, you will need to add
+`-DLLVM_ENABLE_RTTI=on`.
+
+### Gentoo Linux
+
+To build **ccls** on Gentoo Linux with system Clang+LLVM, you will need to add
+`-DLLVM_ENABLE_RTTI=on`.
+
+### Debian / Ubuntu
+
+To build from source you'll need `sudo apt install zlib1g-dev ncurses-dev`
+
+On Ubuntu 16.04 install g++-7 via [these directions](https://gist.github.com/jlblancoc/99521194aba975286c80f93e47966dc5)
+
+### Red Hat / CentOS
+
+Older versions (6.x) use an older GNU libc which requires
+`-DCMAKE_CXX_FLAGS=-D__STDC_FORMAT_MACROS`
+
+## MacOS
+
+To install **ccls** with Homebrew use https://github.com/twlz0ne/homebrew-ccls
+
+To build from source you need MacOS 10.12 (Sierra) or higher to get a version
+of Xcode with a sufficiently-new Clang.
+
+To build using MacPorts Clang add CMake flags `-DSYSTEM_CLANG=on
+-DCMAKE_CXX_COMPILER=clang++-mp-6.0
+-DCMAKE_PREFIX_PATH=/opt/local/libexec/llvm-6.0 -DLLVM_ENABLE_RTTI=on
+-DUSE_SHARED_LLVM=on`
+
+## FreeBSD
+
+* [devel/ccls](https://www.freshports.org/devel/ccls)
+* With `devel/llvm70` add CMake flags `-DSYSTEM_CLANG=on
+  -DUSE_SHARED_LLVM=on -DCMAKE_PREFIX_PATH=/usr/local/llvm70`
+* To use the releases.llvm.org prebuilt archive and its libc++ add CMake flag
+  `-DCLANG_USE_BUNDLED_LIBC++=on`
 
 ## Windows
 
-The Windows archive on releases.llvm.org does not contain library headers, since ccls uses Clang C++ APIs, it is not possible to build ccls with these releases. You have to either:
+The Windows archive on releases.llvm.org does not contain library headers.
+Since **ccls** uses Clang C++ APIs, it is not possible to build **ccls** with
+these releases.  You must either:
 
 1. Build LLVM+Clang by yourself with your favorite toolchain.
 2. Get prebuilt LLVM+Clang from other sources.
@@ -90,20 +188,22 @@ cmake .. -G Ninja  -DSYSTEM_CLANG=ON -DCMAKE_CXX_FLAGS=-D__STDC_FORMAT_MACROS
 cmake --build  .
 ```
 
-Building ccls with MSVC 2017 and locally built LLVM+Clang on Windows does not work right now, contributions welcome.
+Building ccls with MSVC 2017 and locally built LLVM+Clang on Windows does not
+work right now, contributions welcome.
 
 `-D__STDC_FORMAT_MACROS` is because otherwise `mingw-w64-headers/crt/inttypes.h` does not define `PRIu64`.
 
-## Link against clang+llvm libraries compiled from source
+## Notes on compiling Clang+LLVM from source
 
 * `include/llvm/Config/config.h`
 * `include/clang/Config/config.h`
 * `lib/libclangIndex.so`
-* `lib/libLLVM{Support,...}.so` or `lib/libLLVM{Support,...}.a` or `lib/libLLVM.so`
+* `lib/libLLVM{Support,...}.so` or `lib/libLLVM{Support,...}.a` or
+  `lib/libLLVM.so`
 
 MaskRay's config (building trunk LLVM at `~/llvm/Release/`):
 
-```zsh
+```sh
 git clone https://git.llvm.org/git/llvm.git
 git clone https://git.llvm.org/git/clang.git llvm/tools/clang
 cd llvm
@@ -117,7 +217,7 @@ ninja -C Release clangFormat clangFrontendTool clangIndex clangTooling
 
 Then build ccls with `-DSYSTEM_CLANG` and `-DCMAKE_PREFIX_PATH`:
 
-```zsh
+```sh
 cd ~/ccls
 cmake -H. -BRelease -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_EXE_LINKER_FLAGS=-fuse-ld=lld -DSYSTEM_CLANG=On -DCMAKE_PREFIX_PATH="$HOME/llvm/Release;$HOME/llvm/Release/tools/clang;$HOME/llvm;$HOME/llvm/tools/clang"
 ninja -C Release