diff --git a/Jamroot.jam b/Jamroot.jam
index 28a8c0e80..2e01fe760 100644
--- a/Jamroot.jam
+++ b/Jamroot.jam
@@ -162,9 +162,7 @@ local unix_os = [ set.difference [ feature.values <target-os> ] : windows vms ]
 exe b2
     :   $(b2_src)
         python
-    :   <target-os>windows:<define>NT
-        <target-os>windows:<source>$(b2_src_nt)
-        <target-os>vms:<define>VMS
+    :   <target-os>windows:<source>$(b2_src_nt)
         <target-os>vms:<source>$(b2_src_vms)
         <target-os>$(unix_os):<source>$(b2_src_unix)
         <dependency>jamgram.cpp
diff --git a/src/engine/build.bat b/src/engine/build.bat
index 7543adf54..8f8f9c779 100644
--- a/src/engine/build.bat
+++ b/src/engine/build.bat
@@ -183,7 +183,7 @@ set B2_SOURCES=%B2_SOURCES% modules/regex.cpp
 set B2_SOURCES=%B2_SOURCES% modules/sequence.cpp
 set B2_SOURCES=%B2_SOURCES% modules/set.cpp
 
-set B2_CXXFLAGS=%B2_CXXFLAGS% -DNT -DNDEBUG
+set B2_CXXFLAGS=%B2_CXXFLAGS% -DNDEBUG
 
 @echo ON
 %B2_CXX% %CXXFLAGS% %B2_CXXFLAGS% %B2_SOURCES% %B2_CXX_LINK%
diff --git a/src/engine/build.sh b/src/engine/build.sh
index 79462698b..9327bdd71 100755
--- a/src/engine/build.sh
+++ b/src/engine/build.sh
@@ -170,7 +170,7 @@ case $B2_TOOLSET in
         if test -r ${B2_TOOLSET_ROOT}bin/gcc ; then
             export PATH=${B2_TOOLSET_ROOT}bin:$PATH
         fi
-        B2_CXX="${CXX} -x c++ -DNT"
+        B2_CXX="${CXX} -x c++ -std=c++11"
         B2_CXXFLAGS_RELEASE="-O2 -s"
         B2_CXXFLAGS_DEBUG="-O0 -g"
         B2_OS="NT"
diff --git a/src/engine/config.h b/src/engine/config.h
index 6260f5a7b..9ff147d8e 100644
--- a/src/engine/config.h
+++ b/src/engine/config.h
@@ -17,4 +17,18 @@ http://www.boost.org/LICENSE_1_0.txt)
 #define OPT_FIX_TARGET_VARIABLES_EXT 1
 #define OPT_IMPROVED_PATIENCE_EXT 1
 
+// Autodetect various operating systems..
+
+#if defined(_WIN32) || defined(_WIN64) || \
+    defined(__WIN32__) || defined(__TOS_WIN__) || \
+    defined(__WINDOWS__)
+    #define NT 1
+#endif
+
+#if defined(__VMS) || defined(__VMS_VER)
+    #if !defined(VMS)
+        #define VMS 1
+    #endif
+#endif
+
 #endif