Index: ps/trunk/build/workspaces/update-workspaces.sh
===================================================================
--- ps/trunk/build/workspaces/update-workspaces.sh
+++ ps/trunk/build/workspaces/update-workspaces.sh
@@ -38,6 +38,7 @@
 
 premake_args=""
 
+with_system_premake5=false
 without_nvtt=false
 with_system_nvtt=false
 with_system_mozjs45=false
@@ -46,6 +47,7 @@
 for i in "$@"
 do
   case $i in
+    --with-system-premake5 ) with_system_premake5=true ;;
     --without-nvtt ) without_nvtt=true; premake_args="${premake_args} --without-nvtt" ;;
     --with-system-nvtt ) with_system_nvtt=true; premake_args="${premake_args} --with-system-nvtt" ;;
     --with-system-mozjs45 ) with_system_mozjs45=true; premake_args="${premake_args} --with-system-mozjs45" ;;
@@ -95,22 +97,29 @@
   echo
 fi
 
-# Now build premake and run it to create the makefiles
-cd ../premake/premake5
-PREMAKE_BUILD_DIR=build/gmake.unix
-# BSD and OS X need different Makefiles
-case "`uname -s`" in
-  "GNU/kFreeBSD" )
-    # use default gmake.unix (needs -ldl as we have a GNU userland and libc)
-    ;;
-  *"BSD" )
-    PREMAKE_BUILD_DIR=build/gmake.bsd
-    ;;
-  "Darwin" )
-    PREMAKE_BUILD_DIR=build/gmake.macosx
-    ;;
-esac
-${MAKE} -C $PREMAKE_BUILD_DIR ${JOBS} || die "Premake build failed"
+# Now run premake to create the makefiles
+
+premake_command="premake5"
+if [ "$with_system_premake5" = "false" ]; then
+  # Build bundled premake
+  cd ../premake/premake5
+  PREMAKE_BUILD_DIR=build/gmake.unix
+  # BSD and OS X need different Makefiles
+  case "`uname -s`" in
+    "GNU/kFreeBSD" )
+      # use default gmake.unix (needs -ldl as we have a GNU userland and libc)
+      ;;
+    *"BSD" )
+      PREMAKE_BUILD_DIR=build/gmake.bsd
+      ;;
+    "Darwin" )
+      PREMAKE_BUILD_DIR=build/gmake.macosx
+      ;;
+  esac
+  ${MAKE} -C $PREMAKE_BUILD_DIR ${JOBS} || die "Premake build failed"
+
+  premake_command="premake5/bin/release/premake5"
+fi
 
 echo
 
@@ -121,11 +130,11 @@
 
 echo "Premake args: ${premake_args}"
 if [ "`uname -s`" != "Darwin" ]; then
-  premake5/bin/release/premake5 --file="premake5.lua" --outpath="../workspaces/gcc/" ${premake_args} gmake || die "Premake failed"
+  ${premake_command} --file="premake5.lua" --outpath="../workspaces/gcc/" ${premake_args} gmake || die "Premake failed"
 else
-  premake5/bin/release/premake5 --file="premake5.lua" --outpath="../workspaces/gcc/" --macosx-version-min="${MIN_OSX_VERSION}" ${premake_args} gmake || die "Premake failed"
+  ${premake_command} --file="premake5.lua" --outpath="../workspaces/gcc/" --macosx-version-min="${MIN_OSX_VERSION}" ${premake_args} gmake || die "Premake failed"
   # Also generate xcode workspaces if on OS X
-  premake5/bin/release/premake5 --file="premake5.lua" --outpath="../workspaces/xcode4" --macosx-version-min="${MIN_OSX_VERSION}" ${premake_args} xcode4 || die "Premake failed"
+  ${premake_command} --file="premake5.lua" --outpath="../workspaces/xcode4" --macosx-version-min="${MIN_OSX_VERSION}" ${premake_args} xcode4 || die "Premake failed"
 fi
 
 # test_root.cpp gets generated by cxxtestgen and passing different arguments to premake could require a regeneration of this file.