diff --git a/cmake/UpdateCacheVariable.cmake b/cmake/UpdateCacheVariable.cmake
new file mode 100644
index 0000000..82ae571
--- /dev/null
+++ b/cmake/UpdateCacheVariable.cmake
@@ -0,0 +1,48 @@
+# Ceres Solver - A fast non-linear least squares minimizer
+# Copyright 2015 Google Inc. All rights reserved.
+# http://ceres-solver.org/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+#   this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+# * Neither the name of Google Inc. nor the names of its contributors may be
+#   used to endorse or promote products derived from this software without
+#   specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+# Author: alexs.mac@gmail.com (Alex Stewart)
+
+# By default, there is no easy way in CMake to set the value of a cache
+# variable without reinitialising it, which involves resetting its
+# associated help string.  This is particularly annoying for CMake options
+# where they need to programmatically updated.
+#
+# This function automates this process by getting the current help string
+# for the cache variable to update, then reinitialising it with the new
+# value, but with the original help string.
+function(UPDATE_CACHE_VARIABLE VAR_NAME VALUE)
+  get_property(IS_DEFINED_IN_CACHE CACHE ${VAR_NAME} PROPERTY VALUE SET)
+  if (NOT IS_DEFINED_IN_CACHE)
+    message(FATAL_ERROR "Specified variable to update in cache: "
+      "${VAR_NAME} has not been set in the cache.")
+  endif()
+  get_property(HELP_STRING CACHE ${VAR_NAME} PROPERTY HELPSTRING)
+  get_property(VAR_TYPE CACHE ${VAR_NAME} PROPERTY TYPE)
+  set(${VAR_NAME} ${VALUE} CACHE ${VAR_TYPE} "${HELP_STRING}" FORCE)
+endfunction()