diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 7fdb6289..32009969 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -10,10 +10,16 @@ AC_CONFIG_AUX_DIR([autoconf])
 AC_DEFUN([AX_LLVM_HOME],[
     AC_ARG_WITH([llvm],
                 AS_HELP_STRING([--with-llvm@<:@=DIR@:>@], [LLVM root directory]),
-                [LLVM_HOME="$withval"],
-                [LLVM_HOME="/usr"]
+                [LLVM_HOME="$withval"
+                 AC_PATH_PROG(LLVM_CONFIG, llvm-config, no-llvm-config, "$LLVM_HOME/bin")
+                 AS_IF([test "$ac_cv_path_LLVM_CONFIG" = "no-llvm-config"],AC_MSG_ERROR([could not find llvm-config]),[])
+                ],
+                [
+                 AC_PATH_PROG(LLVM_CONFIG, llvm-config, no-llvm-config, "/bin:/usr/bin:/usr/local/bin:/sw/bin:/usr/local/opt/llvm/bin")
+                 AS_IF([test "$ac_cv_path_LLVM_CONFIG" = "no-llvm-config"],AC_MSG_ERROR([could not find llvm-config]),[])
+                 LLVM_HOME=`$LLVM_CONFIG --prefix`
+                ]
                )
-    AC_SUBST([LLVM_HOME])
 ])
 
 dnl Test if clang will link successfully.  Some systems like Ubuntu 16.04 shipping with clang that does not work.
@@ -40,12 +46,14 @@ AC_DEFUN([AX_HDF5_HOME],[
                 [HDF5_HOME="$withval"
                  AS_IF([test "$HDF5_HOME" = "yes"],
                   AC_CHECK_HEADER(hdf5.h,[HDF5_HOME="/usr"],AC_MSG_ERROR([could not find hdf5.h])),
-                  AC_CHECK_FILE([$HDF5_HOME/include/hdf5.h],
-                               [],
-                               AC_MSG_ERROR([could not find $HDF5_HOME/include/hdf5.h])
-                              )
+                  AS_IF([test "$HDF5_HOME" = "no"],[HDF5_HOME=""],
+                   AC_CHECK_FILE([$HDF5_HOME/include/hdf5.h],
+                                 [],
+                                 AC_MSG_ERROR([could not find $HDF5_HOME/include/hdf5.h])
+                                )
+                  )
                 )],
-                [HDF5_HOME=""]
+                [AC_CHECK_HEADER(hdf5.h, [HDF5_HOME="/usr"], [HDF5_HOME=""])]
                )
     AC_SUBST([HDF5_HOME])
 ])
@@ -100,12 +108,14 @@ AC_DEFUN([AX_GSL_HOME],[
                 [GSL_HOME="$withval"
                  AS_IF([test "$GSL_HOME" = "yes"],
                   AC_CHECK_HEADER(gsl/gsl_rng.h,[GSL_HOME="/usr"],AC_MSG_ERROR([could not find gsl/gsl_rng.h])),
-                  AC_CHECK_FILE([$GSL_HOME/include/gsl],
-                               [],
-                               AC_MSG_ERROR([could not find $GSL_HOME/include/gsl])
-                              )
+                  AS_IF([test "$GSL_HOME" = "no"],[GSL_HOME=""],
+                    AC_CHECK_FILE([$GSL_HOME/include/gsl],
+                                  [],
+                                  AC_MSG_ERROR([could not find $GSL_HOME/include/gsl])
+                                 )
+                  )
                 )],
-                [GSL_HOME=""]
+                [AC_CHECK_HEADER(gsl/gsl_rng.h, [GSL_HOME="/usr"], [GSL_HOME=""])]
                )
     AC_SUBST([GSL_HOME])
 ])
@@ -116,12 +126,14 @@ AC_DEFUN([AX_GTEST_HOME],[
                 [GTEST_HOME="$withval"
                  AS_IF([test "$GTEST_HOME" = "yes"],
                   AC_CHECK_HEADER(gtest/gtest.h,[GTEST_HOME="/usr"],AC_MSG_ERROR([could not find gtest/gtest.h])),
-                  AC_CHECK_FILE([$GTEST_HOME/include/gtest],
-                               [],
-                               AC_MSG_ERROR([could not find $GTEST_HOME/include/gtest])
-                              )
+                  AS_IF([test "$GTEST_HOME" = "no"],[GTEST_HOME=""],
+                    AC_CHECK_FILE([$GTEST_HOME/include/gtest],
+                                  [],
+                                  AC_MSG_ERROR([could not find $GTEST_HOME/include/gtest])
+                                 )
+                  )
                 )],
-                [GTEST_HOME=""]
+                [AC_CHECK_HEADER(gtest/gtest.h, [GTEST_HOME="/usr"], [GTEST_HOME=""])]
                )
     AC_SUBST([GTEST_HOME])
 ])
@@ -178,8 +190,6 @@ AS_IF([test "x$GCC_VERSION" = "x"],[],
     AC_MSG_ERROR([Trick requires gcc version >= 4.8])
    ])
 ])
-dnl AC_PATH_PROG(CC, $CC, no_cc)
-dnl AC_PATH_PROG(CXX, $CXX, no_cxx)
 dnl Save the full path of the compiler
 CC=`which $CC`
 CXX=`which $CXX`
@@ -228,16 +238,16 @@ AX_PROG_PERL_MODULES( Digest::MD5,[],AC_MSG_ERROR([could not find perl module Di
 
 dnl process the optional --with-llvm command line arguments
 AX_LLVM_HOME([])
-AC_PATH_PROG(LLVM_CONFIG, llvm-config, no-llvm-config, "$LLVM_HOME/bin:/bin:/usr/bin:/usr/local/bin:/sw/bin")
-AS_IF([test "$ac_cv_path_LLVM_CONFIG" = "no-llvm-config"],AC_MSG_ERROR([could not find clang]),[])
 LLVM_LIB_DIR=`$LLVM_CONFIG --libdir`
 LLVM_BIN_DIR=`$LLVM_CONFIG --bindir`
 AC_CHECK_FILE([$LLVM_LIB_DIR/libLLVMSupport.a],
   [],
   AC_MSG_ERROR([could not find clang library files in $LLVM_LIB_DIR])
 )
-AC_PATH_PROG(CLANG, clang, noclang, "$LLVM_BIN_DIR:$LLVM_HOME/bin:/bin:/usr/bin:/usr/local/bin:/sw/bin")
+AC_PATH_PROG(CLANG, clang, noclang, "$LLVM_BIN_DIR:/bin:/usr/bin:/usr/local/bin:/sw/bin")
 AS_IF([test "$ac_cv_path_CLANG" = "noclang"],AC_MSG_ERROR([could not find clang]),[])
+AC_SUBST([LLVM_HOME])
+
 dnl does not work under RedHat 6
 dnl AX_TEST_CLANG
 
@@ -277,3 +287,5 @@ AX_ER7_UTILS([])
 
 AC_OUTPUT([share/trick/makefiles/config_user.mk])
 
+printf "\033@<:@32mconfigure script successfully completed\033@<:@0m\n"
+
diff --git a/configure b/configure
index 96ffc7fe..2982c3b7 100755
--- a/configure
+++ b/configure
@@ -630,9 +630,9 @@ HDF5_HOME
 UDUNITS_LDFLAGS
 UDUNITS_INCLUDES
 UDUNITS_HOME
+LLVM_HOME
 CLANG
 LLVM_CONFIG
-LLVM_HOME
 PYTHON_EXTRA_LIBS
 PYTHON_EXTRA_LDFLAGS
 PYTHON_SITE_PKG
@@ -7060,14 +7060,7 @@ fi
 # Check whether --with-llvm was given.
 if test "${with_llvm+set}" = set; then :
   withval=$with_llvm; LLVM_HOME="$withval"
-else
-  LLVM_HOME="/usr"
-
-fi
-
-
-
-# Extract the first word of "llvm-config", so it can be a program name with args.
+                 # Extract the first word of "llvm-config", so it can be a program name with args.
 set dummy llvm-config; ac_word=$2
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
 $as_echo_n "checking for $ac_word... " >&6; }
@@ -7080,7 +7073,54 @@ else
   ;;
   *)
   as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-as_dummy=""$LLVM_HOME/bin:/bin:/usr/bin:/usr/local/bin:/sw/bin""
+for as_dir in "$LLVM_HOME/bin"
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_LLVM_CONFIG="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  test -z "$ac_cv_path_LLVM_CONFIG" && ac_cv_path_LLVM_CONFIG="no-llvm-config"
+  ;;
+esac
+fi
+LLVM_CONFIG=$ac_cv_path_LLVM_CONFIG
+if test -n "$LLVM_CONFIG"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $LLVM_CONFIG" >&5
+$as_echo "$LLVM_CONFIG" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+                 if test "$ac_cv_path_LLVM_CONFIG" = "no-llvm-config"; then :
+  as_fn_error $? "could not find llvm-config" "$LINENO" 5
+fi
+
+else
+
+                 # Extract the first word of "llvm-config", so it can be a program name with args.
+set dummy llvm-config; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_LLVM_CONFIG+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  case $LLVM_CONFIG in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_LLVM_CONFIG="$LLVM_CONFIG" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+as_dummy=""/bin:/usr/bin:/usr/local/bin:/sw/bin:/usr/local/opt/llvm/bin""
 for as_dir in $as_dummy
 do
   IFS=$as_save_IFS
@@ -7109,9 +7149,15 @@ $as_echo "no" >&6; }
 fi
 
 
-if test "$ac_cv_path_LLVM_CONFIG" = "no-llvm-config"; then :
-  as_fn_error $? "could not find clang" "$LINENO" 5
+                 if test "$ac_cv_path_LLVM_CONFIG" = "no-llvm-config"; then :
+  as_fn_error $? "could not find llvm-config" "$LINENO" 5
 fi
+                 LLVM_HOME=`$LLVM_CONFIG --prefix`
+
+
+fi
+
+
 LLVM_LIB_DIR=`$LLVM_CONFIG --libdir`
 LLVM_BIN_DIR=`$LLVM_CONFIG --bindir`
 as_ac_File=`$as_echo "ac_cv_file_$LLVM_LIB_DIR/libLLVMSupport.a" | $as_tr_sh`
@@ -7151,7 +7197,7 @@ else
   ;;
   *)
   as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-as_dummy=""$LLVM_BIN_DIR:$LLVM_HOME/bin:/bin:/usr/bin:/usr/local/bin:/sw/bin""
+as_dummy=""$LLVM_BIN_DIR:/bin:/usr/bin:/usr/local/bin:/sw/bin""
 for as_dir in $as_dummy
 do
   IFS=$as_save_IFS
@@ -7186,6 +7232,8 @@ fi
 
 
 
+
+
 # Check whether --with-udunits was given.
 if test "${with_udunits+set}" = set; then :
   withval=$with_udunits; UDUNITS_HOME="$withval"
@@ -7288,6 +7336,9 @@ else
 fi
 
 
+else
+  if test "$HDF5_HOME" = "no"; then :
+  HDF5_HOME=""
 else
   as_ac_File=`$as_echo "ac_cv_file_$HDF5_HOME/include/hdf5.h" | $as_tr_sh`
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $HDF5_HOME/include/hdf5.h" >&5
@@ -7315,8 +7366,17 @@ fi
 
 
 fi
+
+fi
+else
+  ac_fn_cxx_check_header_mongrel "$LINENO" "hdf5.h" "ac_cv_header_hdf5_h" "$ac_includes_default"
+if test "x$ac_cv_header_hdf5_h" = xyes; then :
+  HDF5_HOME="/usr"
 else
   HDF5_HOME=""
+fi
+
+
 
 fi
 
@@ -7458,6 +7518,9 @@ else
 fi
 
 
+else
+  if test "$GSL_HOME" = "no"; then :
+  GSL_HOME=""
 else
   as_ac_File=`$as_echo "ac_cv_file_$GSL_HOME/include/gsl" | $as_tr_sh`
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $GSL_HOME/include/gsl" >&5
@@ -7485,8 +7548,17 @@ fi
 
 
 fi
+
+fi
+else
+  ac_fn_cxx_check_header_mongrel "$LINENO" "gsl/gsl_rng.h" "ac_cv_header_gsl_gsl_rng_h" "$ac_includes_default"
+if test "x$ac_cv_header_gsl_gsl_rng_h" = xyes; then :
+  GSL_HOME="/usr"
 else
   GSL_HOME=""
+fi
+
+
 
 fi
 
@@ -7506,6 +7578,9 @@ else
 fi
 
 
+else
+  if test "$GTEST_HOME" = "no"; then :
+  GTEST_HOME=""
 else
   as_ac_File=`$as_echo "ac_cv_file_$GTEST_HOME/include/gtest" | $as_tr_sh`
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $GTEST_HOME/include/gtest" >&5
@@ -7533,8 +7608,17 @@ fi
 
 
 fi
+
+fi
+else
+  ac_fn_cxx_check_header_mongrel "$LINENO" "gtest/gtest.h" "ac_cv_header_gtest_gtest_h" "$ac_includes_default"
+if test "x$ac_cv_header_gtest_gtest_h" = xyes; then :
+  GTEST_HOME="/usr"
 else
   GTEST_HOME=""
+fi
+
+
 
 fi
 
@@ -8715,3 +8799,5 @@ $as_echo "$as_me: WARNING: unrecognized options: $ac_unrecognized_opts" >&2;}
 fi
 
 
+printf "\033[32mconfigure script successfully completed\033[0m\n"
+