diff --git a/cmake/modules/TableGen.cmake b/cmake/modules/TableGen.cmake
index f6da1b8..cf7cd1f 100644
--- a/cmake/modules/TableGen.cmake
+++ b/cmake/modules/TableGen.cmake
@@ -6,10 +6,16 @@
   file(GLOB local_tds "*.td")
   file(GLOB_RECURSE global_tds "${LLVM_MAIN_SRC_DIR}/include/llvm/*.td")
 
+  if (IS_ABSOLUTE ${LLVM_TARGET_DEFINITIONS})
+    set(LLVM_TARGET_DEFINITIONS_ABSOLUTE ${LLVM_TARGET_DEFINITIONS})
+  else()
+    set(LLVM_TARGET_DEFINITIONS_ABSOLUTE 
+      ${CMAKE_CURRENT_SOURCE_DIR}/${LLVM_TARGET_DEFINITIONS})
+  endif()
   add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${ofn}
     COMMAND ${LLVM_TABLEGEN_EXE} ${ARGN} -I ${CMAKE_CURRENT_SOURCE_DIR}
     -I ${LLVM_MAIN_SRC_DIR}/lib/Target -I ${LLVM_MAIN_INCLUDE_DIR}
-    ${CMAKE_CURRENT_SOURCE_DIR}/${LLVM_TARGET_DEFINITIONS} 
+    ${LLVM_TARGET_DEFINITIONS_ABSOLUTE} 
     -o ${CMAKE_CURRENT_BINARY_DIR}/${ofn}
     DEPENDS tblgen ${local_tds} ${global_tds}
     COMMENT "Building ${ofn}..."