第一步，首先编辑 /etc/apt/sources.list,增加下面源：

(加入源后务必执行apt-get update,假设有错误提示，先执行第二步，然后apt-get update）

Debian平台：

deb http://llvm.org/apt/wheezy/ llvm-toolchain-wheezy main

deb-src http://llvm.org/apt/wheezy/ llvm-toolchain-wheezy main

deb http://llvm.org/apt/unstable/ llvm-toolchain main

deb-src http://llvm.org/apt/unstable/ llvm-toolchain main

# 3.4

deb http://llvm.org/apt/unstable/ llvm-toolchain-3.4 main

deb-src http://llvm.org/apt/unstable/ llvm-toolchain-3.4 main

# 3.5

deb http://llvm.org/apt/unstable/ llvm-toolchain-3.5 main

deb-src http://llvm.org/apt/unstable/ llvm-toolchain-3.5 main

Ubuntu平台：

deb http://llvm.org/apt/precise/ llvm-toolchain-precise main

deb-src http://llvm.org/apt/precise/ llvm-toolchain-precise main

# 3.4

deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.4 main

deb-src http://llvm.org/apt/precise/ llvm-toolchain-precise-3.4 main

# 3.5

deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.5 main

deb-src http://llvm.org/apt/precise/ llvm-toolchain-precise-3.5 main

# Common

deb http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu precise main

deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty main

deb-src http://llvm.org/apt/trusty/ llvm-toolchain-trusty main

# 3.4

deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.4 main

deb-src http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.4 main

# 3.5

deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.5 main

deb-src http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.5 main

第二步，安装前必须取得相关证书

wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key|sudo apt-key add -

第三步，能够開始用apt安装了

apt-get install clang-3.4 lldb-3.4

To install all packages:

apt-get install clang-3.4 clang-3.4-doc libclang-common-3.4-dev libclang-3.4-dev libclang1-3.4 libclang1-3.4-dbg libllvm-3.4-ocaml-dev libllvm3.4 libllvm3.4-dbg lldb-3.4 llvm-3.4 llvm-3.4-dev
llvm-3.4-doc llvm-3.4-examples llvm-3.4-runtime clang-modernize-3.4 clang-format-3.4 python-clang-3.4 lldb-3.4-dev