How to make Visual Studio use the native amd64 toolchain

If your goal is to use the native environment rather than specifically amd64_x86, you can set the UseNativeEnvironment property in your project file:

<PropertyGroup>
  <UseNativeEnvironment>true</UseNativeEnvironment>
</PropertyGroup>

(I have successfully added it to the "Globals" PropertyGroup.)

You can check which toolchain is being used by adding the /Bv compiler option. Example output is below. Notice that the toolchain directory appears after bin\ (amd64_x86 in this case).

2>ClCompile:
2>  Compiler Passes:
2>   C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64_x86\CL.exe:        Version 18.00.31101.0
2>   C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64_x86\c1.dll:        Version 18.00.31101.0
2>   C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64_x86\c1xx.dll:      Version 18.00.31101.0
2>   C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64_x86\c2.dll:        Version 18.00.31101.0
2>   C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64_x86\link.exe:      Version 12.00.31101.0
2>   C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64\mspdb120.dll:      Version 12.00.31101.0
2>   C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64_x86\1033\clui.dll: Version 18.00.31101.0

You need to set the environment variable "_IsNativeEnvironment" to "true" prior to starting Visual Studio 2012 IDE:

set _IsNativeEnvironment=true
start "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\devenv.exe" your_solution.sln

For Visual Studio 2013, the name of the environment variable is different:

set PreferredToolArchitecture=x64
sbm start "C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe" your_solution.sln

Beware that this technique does not work if the version of the IDE does not match the version of the toolchain. That is, if you use VS2013 IDE configured to run VS2012 compiler, you are out of luck. But such combination is uncommon.

Here are some links for further information:

difference between VS12 and VS13

how to embed PreferredToolArchitecture into the project in VS13

I know this is a rather old post, but it's still relevant for VS 2017. Here you also have the "PreferredToolArchitecture" environment variable and a "build in" setting in the IDE is not readily available.

However you can integrate that easily on a project by project base so that you can always chose what tool architecture to use. Maybe this is helpful for some. Do this:

• Go to Property Manager and create a new property sheet, e. g. named "x64 Toolchain.props" so you know what it does. With a separate property sheet you can then switch the tool architecture as appropriate by including or not including the sheet into a project.
• Open the properties of that new sheet, navigate to "Common Properties\User Macros" and click "Add Macro".
• In the dialog you set the name to "PreferredToolArchitecture", the value to "x64" and enable the checkbox "Set this macro as an environment variable in the build environment".
• Optionally navigate to "Common Properties\C/C++\Command Line" and add "/Bv" under "Additional Options". This will make the compiler output the tools it uses including its path and version number, might be helpful for checking if really the desired architecture is being used. It will place entries in the log output window like so:

  Compiler Passes:
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\bin\HostX86\x64\CL.exe: Version 19.15.26730.0
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\bin\HostX86\x64\c1.dll: Version 19.15.26730.0
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\bin\HostX86\x64\c1xx.dll: Version 19.15.26730.0
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\bin\HostX86\x64\c2.dll: Version 19.15.26730.0
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\bin\HostX86\x64\link.exe: Version 14.15.26730.0
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\bin\HostX86\x86\mspdb140.dll: Version 14.15.26730.0
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\bin\HostX86\x64\1033\clui.dll: Version 19.15.26730.0
  

• Now for all projects that should be build with the x64 tool architecture include the new property sheet into the project in property manager. And for those that should not simply don't include it. That's it.

HTH

Edit: It seems unfortunately this is not reliable! See below comments. I would really appreciate if MS would wire this setting to some GUI element and make it work consinstently...

There is another method of forcing use of the 64-bit linker on a per-project basis for Visual Studio 2013. Edit your .vcxproj file and insert the following after the <Import...Microsoft.Cpp.Defaults line:

  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
  <PropertyGroup>
    <PreferredToolArchitecture>x64</PreferredToolArchitecture>
  </PropertyGroup>