diff --git a/CMakeLists.txt b/CMakeLists.txt
index f3e69b845..919f43bb2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,11 @@
 # cmake_minimum_require must be the first command of the file
 cmake_minimum_required(VERSION 3.5.0)
 
+# option() honors normal variables.
+if (POLICY CMP0077)
+  cmake_policy(SET CMP0077 NEW)
+endif()
+
 project(Eigen3)
 
 # guard against in-source builds
@@ -21,6 +26,7 @@ if (NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE "Release")
 endif()
 
+option(EIGEN_MPL2_ONLY "Only use MPL2 or more permissive license." OFF)
 
 #############################################################################
 # retrieve version information                                               #
@@ -592,7 +598,12 @@ set ( EIGEN_VERSION_STRING ${EIGEN_VERSION_NUMBER} )
 set ( EIGEN_VERSION_MAJOR  ${EIGEN_WORLD_VERSION} )
 set ( EIGEN_VERSION_MINOR  ${EIGEN_MAJOR_VERSION} )
 set ( EIGEN_VERSION_PATCH  ${EIGEN_MINOR_VERSION} )
-set ( EIGEN_DEFINITIONS "")
+
+if(EIGEN_MPL2_ONLY)
+  set ( EIGEN_DEFINITIONS EIGEN_MPL2_ONLY)
+else()
+  set ( EIGEN_DEFINITIONS "")
+endif()
 set ( EIGEN_INCLUDE_DIR "${CMAKE_INSTALL_PREFIX}/${INCLUDE_INSTALL_DIR}" )
 set ( EIGEN_ROOT_DIR ${CMAKE_INSTALL_PREFIX} )