diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3ad93a28..e5eb09cf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.1)
 project(trick)
 set(TRICK_MAJOR 19)
 set(TRICK_MINOR 1)
diff --git a/CMakeModules/FindLLVM.cmake b/CMakeModules/FindLLVM.cmake
index a9a06bab..2424012f 100644
--- a/CMakeModules/FindLLVM.cmake
+++ b/CMakeModules/FindLLVM.cmake
@@ -107,11 +107,14 @@ else()
     llvm_set(HOST_TARGET host-target)
     llvm_set(INCLUDE_DIRS includedir true)
     llvm_set(ROOT_DIR prefix true)
-    llvm_set(ENABLE_ASSERTIONS assertion-mode)
 
     # The LLVM version string _may_ contain a git/svn suffix, so match only the x.y.z part
     string(REGEX MATCH "^[0-9]+[.][0-9]+[.][0-9]+" LLVM_VERSION_BASE_STRING "${LLVM_VERSION_STRING}")
 
+    if(NOT ${LLVM_VERSION_STRING} MATCHES "^3\\.4\\..*")
+        llvm_set(ENABLE_ASSERTIONS assertion-mode)
+    endif()
+
     # Versions below 4.0 do not support components debuginfomsf and demangle
     if(${LLVM_VERSION_STRING} MATCHES "^3\\..*")
         list(REMOVE_ITEM LLVM_FIND_COMPONENTS "debuginfomsf" index)
@@ -125,7 +128,9 @@ else()
     llvm_set(LDFLAGS ldflags)
     # In LLVM 3.5+, the system library dependencies (e.g. "-lz") are accessed
     # using the separate "--system-libs" flag.
-    llvm_set(SYSTEM_LIBS system-libs)
+    if(NOT ${LLVM_VERSION_STRING} MATCHES "^3\\.4\\..*")
+        llvm_set(SYSTEM_LIBS system-libs)
+    endif()
     string(REPLACE "\n" " " LLVM_LDFLAGS "${LLVM_LDFLAGS} ${LLVM_SYSTEM_LIBS}")
     string(STRIP ${LLVM_LDFLAGS} LLVM_LDFLAGS)
     llvm_set(LIBRARY_DIRS libdir true)
@@ -150,10 +155,12 @@ else()
 
     # Parse LLVM_NATIVE_ARCH manually from LLVMConfig.cmake; including it leads to issues like
     # https://github.com/ldc-developers/ldc/issues/3079.
-    file(STRINGS "${LLVM_CMAKEDIR}/LLVMConfig.cmake" LLVM_NATIVE_ARCH LIMIT_COUNT 1 REGEX "^set\\(LLVM_NATIVE_ARCH (.+)\\)$")
-    string(REGEX MATCH "set\\(LLVM_NATIVE_ARCH (.+)\\)" LLVM_NATIVE_ARCH "${LLVM_NATIVE_ARCH}")
-    set(LLVM_NATIVE_ARCH ${CMAKE_MATCH_1})
-    message(STATUS "LLVM_NATIVE_ARCH: ${LLVM_NATIVE_ARCH}")
+    if(EXISTS "${LLVM_CMAKEDIR}/LLVMConfig.cmake")
+        file(STRINGS "${LLVM_CMAKEDIR}/LLVMConfig.cmake" LLVM_NATIVE_ARCH LIMIT_COUNT 1 REGEX "^set\\(LLVM_NATIVE_ARCH (.+)\\)$")
+        string(REGEX MATCH "set\\(LLVM_NATIVE_ARCH (.+)\\)" LLVM_NATIVE_ARCH "${LLVM_NATIVE_ARCH}")
+        set(LLVM_NATIVE_ARCH ${CMAKE_MATCH_1})
+        message(STATUS "LLVM_NATIVE_ARCH: ${LLVM_NATIVE_ARCH}")
+    endif()
 endif()
 
 # On CMake builds of LLVM, the output of llvm-config --cxxflags does not
@@ -180,6 +187,7 @@ endif()
 
 string(REGEX REPLACE "([0-9]+).*" "\\1" LLVM_VERSION_MAJOR "${LLVM_VERSION_STRING}" )
 string(REGEX REPLACE "[0-9]+\\.([0-9]+).*[A-Za-z]*" "\\1" LLVM_VERSION_MINOR "${LLVM_VERSION_STRING}" )
+string(REGEX REPLACE "[0-9]+\\.[0-9]+\\.([0-9]+).*[A-Za-z]*" "\\1" LLVM_VERSION_PATCH "${LLVM_VERSION_STRING}" )
 
 if (${LLVM_VERSION_STRING} VERSION_LESS ${LLVM_FIND_VERSION})
     message(FATAL_ERROR "Unsupported LLVM version found ${LLVM_VERSION_STRING}. At least version ${LLVM_FIND_VERSION} is required.")
diff --git a/trick_source/codegen/Interface_Code_Gen/CMakeLists.txt b/trick_source/codegen/Interface_Code_Gen/CMakeLists.txt
index d9b5271c..088d4863 100644
--- a/trick_source/codegen/Interface_Code_Gen/CMakeLists.txt
+++ b/trick_source/codegen/Interface_Code_Gen/CMakeLists.txt
@@ -25,15 +25,14 @@ set ( ICG_SRC
 
 add_executable( trick-ICG ${ICG_SRC} )
 target_compile_options( trick-ICG PUBLIC -g -DTRICK_VERSION="${TRICK_MAJOR}.${TRICK_MINOR}.${TRICK_TINY}" -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS)
-target_compile_options( trick-ICG PUBLIC -DLIBCLANG_MAJOR=${LLVM_VERSION_MAJOR} -DLIBCLANG_MINOR=${LLVM_VERSION_MINOR})
 target_compile_options( trick-ICG PUBLIC -DEXTERNAL_BUILD)
+target_compile_options( trick-ICG PUBLIC -DLLVM_HOME="${LLVM_ROOT_DIR}")
+target_compile_options( trick-ICG PUBLIC -DLIBCLANG_MAJOR=${LLVM_VERSION_MAJOR} -DLIBCLANG_MINOR=${LLVM_VERSION_MINOR} -DLIBCLANG_PATCHLEVEL=${LLVM_VERSION_PATCH})
 target_include_directories( trick-ICG PUBLIC ${UDUNITS2_INCLUDES} )
 target_include_directories( trick-ICG PUBLIC ${LLVM_INCLUDE_DIRS} )
 set_property(SOURCE trick-ICG APPEND PROPERTY OBJECT_DEPENDS ${CMAKE_BINARY_DIR}/include/mongoose/mongoose.h)
 
 target_link_libraries( trick-ICG
-    ${LLVM_LDFLAGS}
-    ${LLVM_LIBRARIES}
     -lclangFrontend
     -lclangDriver
     -lclangSerialization
@@ -44,6 +43,8 @@ target_link_libraries( trick-ICG
     -lclangAST
     -lclangLex
     -lclangBasic
+    ${LLVM_LDFLAGS}
+    ${LLVM_LIBRARIES}
     ${UDUNITS2_LIBRARIES}
 )
 
diff --git a/trick_source/codegen/Interface_Code_Gen/HeaderSearchDirs.cpp b/trick_source/codegen/Interface_Code_Gen/HeaderSearchDirs.cpp
index 5dbff5d0..5ee3aa23 100644
--- a/trick_source/codegen/Interface_Code_Gen/HeaderSearchDirs.cpp
+++ b/trick_source/codegen/Interface_Code_Gen/HeaderSearchDirs.cpp
@@ -36,7 +36,6 @@ void HeaderSearchDirs::AddCompilerBuiltInSearchDirs () {
     // Add clang specific include directory first.  Only required on linux systems. :(
     // This is so that ICG will find clang friendly headers first.  gcc headers cause
     // all kinds of problems.  On macs all headers are clang friendly.
-#ifndef EXTERNAL_BUILD
 #if __linux
     std::stringstream icg_dir ;
     icg_dir << LLVM_HOME << "/lib/clang/" ;
@@ -49,7 +48,6 @@ void HeaderSearchDirs::AddCompilerBuiltInSearchDirs () {
     if ( resolved_path != NULL ) {
         hso.AddPath(resolved_path , clang::frontend::System, IsFramework, IsSysRootRelative);
     }
-#endif
 #endif
 
     fp = popen("${TRICK_HOME}/bin/trick-gte TRICK_CXX" , "r") ;