docs: Update build.md for GLSLANG_INSTALL_DIR
diff --git a/BUILD.md b/BUILD.md
index e36693a..5227e0b 100644
--- a/BUILD.md
+++ b/BUILD.md
@@ -40,7 +40,8 @@
 
 - Microsoft Visual Studio 2013 Update 4 Professional, VS2015 (any version), or VS2017 (any version).
 - [glslang](https://github.com/KhronosGroup/glslang)
-  - Ensure that the 'update_glslang_sources.py' script has been run, and the repository successfully built.
+  - Ensure that the 'update_glslang_sources.py' script has been run. Follow the build instructions in the
+    glslang README.md file, noting the location of the chosen install directory.
 - [CMake](http://www.cmake.org/download/)
   - Tell the installer to "Add CMake to the system PATH" environment variable.
 - [Python 3](https://www.python.org/downloads)
@@ -76,9 +77,9 @@
 
 For example, for VS2017 (generators for other versions are [specified here](#cmake-visual-studio-generators)):
 
-    cmake -DLOADER_REPO_ROOT=c:\absolute_path_to\VULKAN_LOADER -DGLSLANG_REPO_ROOT=c:\absolute_path_to\glslang -G "Visual Studio 15 2017 Win64" ..
+    cmake -DLOADER_REPO_ROOT=c:\absolute_path_to\VULKAN_LOADER -DGLSLANG_INSTALL_DIR=c:\absolute_path_to\glslang\install -G "Visual Studio 15 2017 Win64" ..
 
-Both LOADER_REPO_ROOT and GLSLANG_REPO_ROOT each require absolute paths.
+Both LOADER_REPO_ROOT and GLSLANG_INSTALL_DIR each require absolute paths.
 This will create a Windows solution file named `Vulkan-ValidationLayers.sln` in the build directory.
 
 Launch Visual Studio and open the "Vulkan-ValidationLayers.sln" solution file in the build folder.
@@ -139,9 +140,13 @@
 Vulkan Loader Library
   - Building the Layer Validation Tests requires linking to the Vulkan Loader Library (libvulkan-1.so).
       - The LOADER_REPO_ROOT environment variable should be used on the cmake command line to specify a vulkan loader library. Make sure to specify an absoute path, like so:
-      
+
           `cmake -DLOADER_REPO_ROOT=c:\development\Vulkan-Loader ....`
 
+- [glslang](https://github.com/KhronosGroup/glslang)
+  - Ensure that the 'update_glslang_sources.py' script has been run. Follow the build instructions in the
+    glslang README.md file, noting the location of the chosen install directory.
+
 ### Linux Build
 
 Example debug build
@@ -154,7 +159,7 @@
 
         mkdir build
         cd build
-        cmake -DLOADER_REPO_ROOT=/absolute_path_to/Vulkan-Loader -DGLSLANG_REPO_ROOT=/absolute_path_to_/glslang -DCMAKE_BUILD_TYPE=Debug ..
+        cmake -DLOADER_REPO_ROOT=/absolute_path_to/Vulkan-Loader -DGLSLANG_INSTALL_DIR=/absolute_path_to_/glslang/location_of/install -DCMAKE_BUILD_TYPE=Debug ..
 
 4. Run `make -j8` to begin the build
 
@@ -496,11 +501,11 @@
 
 1) Pass in the location of your glslang repository to cmake using absolute paths. From your build directory run:
     1) on Windows
-    
-        `cmake -DGLSLANG_REPO_ROOT=c:/absolute_path_to_your_installation_of/glslang -G "Visual Studio 15 Win64" ..`
+
+        `cmake -DGLSLANG_INSTALL_DIR=c:/absolute_path_to/glslang/location_of/install -G "Visual Studio 15 Win64" ..`
     1) or Linux
-    
-        `cmake -DGLSLANG_REPO_ROOT=/absolute_path_to_your_installation_of/glslang -DCMAKE_BUILD_TYPE=Debug ..`
+
+        `cmake -DGLSLANG_INSTALL_DIR=/absolute_path_to/glslang/location_of/install -DCMAKE_BUILD_TYPE=Debug ..`
 
 2) If building on Windows with MSVC, set `DISABLE_BUILDTGT_DIR_DECORATION` to _On_.
  If building on Windows, but without MSVC set `DISABLE_BUILD_PATH_DECORATION` to _On_