diff --git a/win32/AsmParser/AsmParser.vcproj b/win32/AsmParser/AsmParser.vcproj
index 48162fd22b1..f596b5816f7 100644
--- a/win32/AsmParser/AsmParser.vcproj
+++ b/win32/AsmParser/AsmParser.vcproj
@@ -133,18 +133,16 @@
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Bisoning $(InputFileName)"
-						CommandLine="..\dobison.cmd llvmAsm debug $(InputName) $(InputPath)
-"
-						Outputs="$(InputName).cpp;$(InputName).h"/>
+						CommandLine="..\dobison.cmd llvmAsm debug $(InputName) $(InputPath)"
+						Outputs="$(InputName).cpp;$(InputName).h;$(InputName).output"/>
 				</FileConfiguration>
 				<FileConfiguration
 					Name="Release|Win32">
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Bisoning $(InputFileName)"
-						CommandLine="..\dobison.cmd llvmAsm release $(InputName) $(InputPath)
-"
-						Outputs="$(InputName).cpp;$(InputName).h"/>
+						CommandLine="..\dobison.cmd llvmAsm release $(InputName) $(InputPath)"
+						Outputs="$(InputName).cpp;$(InputName).h;$(InputName).output"/>
 				</FileConfiguration>
 			</File>
 			<File
diff --git a/win32/Configure/Configure.vcproj b/win32/Configure/Configure.vcproj
index 9aca7bd6ab2..0364b1b2ea7 100644
--- a/win32/Configure/Configure.vcproj
+++ b/win32/Configure/Configure.vcproj
@@ -102,7 +102,7 @@ echo #define LLVM_ON_WIN32 1 &gt;&gt;$(ProjectDir)..\llvm\Config\config.h"
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Generating $(SolutionDir)llvm\Support\DataTypes.h"
-            CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\Support\DataTypes.h"
+						CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\Support\DataTypes.h"
 						Outputs="$(ProjectDir)..\llvm\Support\DataTypes.h"/>
 				</FileConfiguration>
 			</File>
@@ -113,7 +113,7 @@ echo #define LLVM_ON_WIN32 1 &gt;&gt;$(ProjectDir)..\llvm\Config\config.h"
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Generating $(SolutionDir)llvm\ADT\hash_map"
-            CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\ADT\hash_map"
+						CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\ADT\hash_map"
 						Outputs="$(ProjectDir)..\llvm\ADT\hash_map"/>
 				</FileConfiguration>
 			</File>
@@ -124,7 +124,7 @@ echo #define LLVM_ON_WIN32 1 &gt;&gt;$(ProjectDir)..\llvm\Config\config.h"
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Generating $(SolutionDir)llvm\ADT\hash_set"
-            CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\ADT\hash_set"
+						CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\ADT\hash_set"
 						Outputs="$(ProjectDir)..\llvm\ADT\hash_set"/>
 				</FileConfiguration>
 			</File>
@@ -135,7 +135,7 @@ echo #define LLVM_ON_WIN32 1 &gt;&gt;$(ProjectDir)..\llvm\Config\config.h"
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Generating $(SolutionDir)llvm\ADT\iterator"
-            CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\ADT\iterator"
+						CommandLine="copy $(InputPath) $(ProjectDir)..\llvm\ADT\iterator"
 						Outputs="$(ProjectDir)..\llvm\ADT\iterator"/>
 				</FileConfiguration>
 			</File>
diff --git a/win32/TableGen/TableGen.vcproj b/win32/TableGen/TableGen.vcproj
index 1c0012a3cf0..0049aee5c9d 100644
--- a/win32/TableGen/TableGen.vcproj
+++ b/win32/TableGen/TableGen.vcproj
@@ -161,18 +161,16 @@
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Bisoning $(InputFileName)"
-						CommandLine="..\dobison.cmd File debug $(InputName) $(InputPath)
-"
-						Outputs="$(InputName).cpp;$(InputName).h"/>
+						CommandLine="..\dobison.cmd File debug $(InputName) $(InputPath)"
+						Outputs="$(InputName).cpp;$(InputName).h;$(InputName).output"/>
 				</FileConfiguration>
 				<FileConfiguration
 					Name="Release|Win32">
 					<Tool
 						Name="VCCustomBuildTool"
 						Description="Bisoning $(InputFileName)"
-						CommandLine="..\dobison.cmd File release $(InputName) $(InputPath)
-"
-						Outputs="$(InputName).cpp;$(InputName).h"/>
+						CommandLine="..\dobison.cmd File release $(InputName) $(InputPath)"
+						Outputs="$(InputName).cpp;$(InputName).h;$(InputName).output"/>
 				</FileConfiguration>
 			</File>
 			<File
diff --git a/win32/dobison.cmd b/win32/dobison.cmd
index c49ae2f3386..27364bb1b5c 100755
--- a/win32/dobison.cmd
+++ b/win32/dobison.cmd
@@ -7,16 +7,16 @@ rem   source - input to bison
 
 if "%2"=="debug" (set flags=-tvdo) else (set flags=-vdo)
 
-rem Try and run bison.  If it is present, great.
-bison -p%1 %flags%%3.cpp %4
-if errorlevel 1 goto error
-move %3.hpp %3.h
-goto done
+rem Test for presence of bison.
+bison --help >NUL
+if errorlevel 1 goto nobison
 
-:error
-echo Bison could not run.  Using pre-generated files.
+rem Run bison.
+bison -p%1 %flags%%3.cpp %4 && move %3.hpp %3.h
+exit
+
+:nobison
+echo Bison not found.  Using pre-generated files.
 copy %~pn4.cpp %3.cpp
 copy %~pn4.h %3.h
-
-:done
-exit 0
+exit
diff --git a/win32/doflex.cmd b/win32/doflex.cmd
index 5c0629d092b..b39d40b7539 100755
--- a/win32/doflex.cmd
+++ b/win32/doflex.cmd
@@ -6,14 +6,15 @@ rem   source - input to bison
 
 if "%1"=="debug" (set flags=-t) else (set flags=-t)
 
-rem Try and run flex.  If it is present, great.
+rem Test for presence of flex.
+flex --help >NUL
+if errorlevel 1 goto noflex
+
+rem Run flex.
 flex %flags% >%2.cpp %3
-if errorlevel 1 goto error
-goto done
+exit
 
-:error
-echo Flex could not run.  Using pre-generated files.
+:noflex
+echo Flex not found.  Using pre-generated files.
 copy %~pn3.cpp %2.cpp
-
-:done
-exit 0
+exit