Merging r340376:

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r340376 | steveire | 2018-08-22 03:11:18 +0200 (Wed, 22 Aug 2018) | 7 lines

Update the docs for using LLVM toolset in Visual Studio

Reviewers: hans

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D51079
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_70@340730 91177308-0d34-0410-b5e6-96231b3b80d8