diff -urN cmake-3.7.2/Modules/Compiler/GNU.cmake cmake-3.7.2-patched/Modules/Compiler/GNU.cmake
--- cmake-3.7.2/Modules/Compiler/GNU.cmake	2017-01-14 00:05:41.000000000 +1000
+++ cmake-3.7.2-patched/Modules/Compiler/GNU.cmake	2017-02-04 11:54:23.332635437 +1000
@@ -36,10 +36,10 @@
 
   # Initial configuration flags.
   string(APPEND CMAKE_${lang}_FLAGS_INIT " ")
-  string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT " -g")
+  string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT "")
   string(APPEND CMAKE_${lang}_FLAGS_MINSIZEREL_INIT " -Os -DNDEBUG")
-  string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -O3 -DNDEBUG")
-  string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -O2 -g -DNDEBUG")
+  string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -DNDEBUG")
+  string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -DNDEBUG")
   set(CMAKE_${lang}_CREATE_PREPROCESSED_SOURCE "<CMAKE_${lang}_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -E <SOURCE> > <PREPROCESSED_SOURCE>")
   set(CMAKE_${lang}_CREATE_ASSEMBLY_SOURCE "<CMAKE_${lang}_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -S <SOURCE> -o <ASSEMBLY_SOURCE>")
   if(NOT APPLE OR NOT CMAKE_${lang}_COMPILER_VERSION VERSION_LESS 4) # work around #4462
diff -urN cmake-3.7.2/Modules/Compiler/GNU-Fortran.cmake cmake-3.7.2-patched/Modules/Compiler/GNU-Fortran.cmake
--- cmake-3.7.2/Modules/Compiler/GNU-Fortran.cmake	2017-01-14 00:05:41.000000000 +1000
+++ cmake-3.7.2-patched/Modules/Compiler/GNU-Fortran.cmake	2017-02-04 11:54:31.535635404 +1000
@@ -9,7 +9,7 @@
 
 # No -DNDEBUG for Fortran.
 string(APPEND CMAKE_Fortran_FLAGS_MINSIZEREL_INIT " -Os")
-string(APPEND CMAKE_Fortran_FLAGS_RELEASE_INIT " -O3")
+string(APPEND CMAKE_Fortran_FLAGS_RELEASE_INIT "")
 
 # No -isystem for Fortran because it will not find .mod files.
 unset(CMAKE_INCLUDE_SYSTEM_FLAG_Fortran)