diff --git a/.travis.yml b/.travis.yml
index b481255d..9692e361 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -251,14 +251,6 @@ matrix:
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
       osx_image: xcode6.4
 
-     - os: linux
-      env: CMAKE_TEST_PROJECT=1
-      install: true
-      script:
-        - mkdir __build__ && cd __build__
-        - cmake ../test
-        - cmake --build .
-
 install:
   - BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
   - cd ..
diff --git a/README.md b/README.md
index d98d250c..3cca3f6d 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,11 @@ This library provides configuration support for the Boost C++ libraries.
 
 The full documentation is available on [boost.org](http://www.boost.org/doc/libs/release/libs/config/index.html).
 
+|                  |  Master  |   Develop   |
+|------------------|----------|-------------|
+| Travis           | [![Build Status](https://travis-ci.org/boostorg/config.svg?branch=master)](https://travis-ci.org/boostorg/config)  |  [![Build Status](https://travis-ci.org/boostorg/config.png)](https://travis-ci.org/boostorg/config) |
+| Appveyor         | [![Build status](https://ci.appveyor.com/api/projects/status/wo2n2mhoy8vegmuo/branch/master?svg=true)](https://ci.appveyor.com/project/jzmaddock/config/branch/master) | [![Build status](https://ci.appveyor.com/api/projects/status/wo2n2mhoy8vegmuo/branch/develop?svg=true)](https://ci.appveyor.com/project/jzmaddock/config/branch/develop) |
+
 ## Support, bugs and feature requests ##
 
 Bugs and feature requests can be reported through the [Gitub issue tracker](https://github.com/boostorg/config/issues)
diff --git a/include/boost/config/compiler/gcc.hpp b/include/boost/config/compiler/gcc.hpp
index 594c44f5..9ae6072e 100644
--- a/include/boost/config/compiler/gcc.hpp
+++ b/include/boost/config/compiler/gcc.hpp
@@ -232,7 +232,6 @@
 // C++0x features in 4.6.n and later
 //
 #if (BOOST_GCC_VERSION < 40600) || !defined(BOOST_GCC_CXX11)
-#define BOOST_NO_CXX11_CONSTEXPR
 #define BOOST_NO_CXX11_DEFAULTED_MOVES
 #define BOOST_NO_CXX11_NOEXCEPT
 #define BOOST_NO_CXX11_NULLPTR
@@ -243,6 +242,9 @@
 // C++0x features in 4.7.n and later
 //
 #if (BOOST_GCC_VERSION < 40700) || !defined(BOOST_GCC_CXX11)
+// Note that while constexpr is partly supported in gcc-4.6 it's a 
+// pre-std version with several bugs:
+#  define BOOST_NO_CXX11_CONSTEXPR
 #  define BOOST_NO_CXX11_FINAL
 #  define BOOST_NO_CXX11_TEMPLATE_ALIASES
 #  define BOOST_NO_CXX11_USER_DEFINED_LITERALS
diff --git a/include/boost/config/platform/cygwin.hpp b/include/boost/config/platform/cygwin.hpp
index 6dd7e57c..d0052d8b 100644
--- a/include/boost/config/platform/cygwin.hpp
+++ b/include/boost/config/platform/cygwin.hpp
@@ -42,8 +42,11 @@
 #   define BOOST_HAS_STDINT_H
 #endif
 
+#include <cygwin/version.h>
+#if (CYGWIN_VERSION_API_MAJOR == 0 && CYGWIN_VERSION_API_MINOR < 231)
 /// Cygwin has no fenv.h
 #define BOOST_NO_FENV_H
+#endif
 
 // Cygwin has it's own <pthread.h> which breaks <shared_mutex> unless the correct compiler flags are used:
 #ifndef BOOST_NO_CXX14_HDR_SHARED_MUTEX
diff --git a/include/boost/version.hpp b/include/boost/version.hpp
index c9afbd98..98ce61a1 100644
--- a/include/boost/version.hpp
+++ b/include/boost/version.hpp
@@ -19,7 +19,7 @@
 //  BOOST_VERSION / 100 % 1000 is the minor version
 //  BOOST_VERSION / 100000 is the major version
 
-#define BOOST_VERSION 106900
+#define BOOST_VERSION 107000
 
 //
 //  BOOST_LIB_VERSION must be defined to be the same as BOOST_VERSION
@@ -27,6 +27,6 @@
 //  number, y is the minor version number, and z is the patch level if not 0.
 //  This is used by <config/auto_link.hpp> to select which library version to link to.
 
-#define BOOST_LIB_VERSION "1_69"
+#define BOOST_LIB_VERSION "1_70"
 
 #endif
diff --git a/test/boost_no_constexpr.ipp b/test/boost_no_constexpr.ipp
index 35ac4891..1f3a96ee 100644
--- a/test/boost_no_constexpr.ipp
+++ b/test/boost_no_constexpr.ipp
@@ -32,13 +32,7 @@ private:
 
 template<int> struct X { };
 
-
-#if __cplusplus < 201400L
-// Some C++14 compilers reject this (clang), some C++11 compilers reject "constexpr const" (GCC-4.6)
-constexpr A a = 42;
-#else
 constexpr const A a = 42;
-#endif
 
 X<a> xx; // OK: unique conversion to int
 
@@ -68,9 +62,18 @@ struct F : virtual E
 };
 constexpr F& f(F& out) { return out; }
 
+namespace whatever{};
+
+constexpr int factorial(int i)
+{
+   typedef int value_type;
+   using namespace whatever;
+   return i <= 1 ? 1 : i * factorial(value_type(i-1));
+}
+
 int test()
 {
-  int i = square(5);
+  constexpr int i = square(5) + factorial(10);
   quiet_warning(i);
 
   switch (i)