diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -2355,9 +2355,12 @@
   endif()
 
   # Enable BUILD_WITH_INSTALL_RPATH unless CMAKE_BUILD_RPATH is set and not
-  # building for macOS or Windows, as those two platforms seemingly require it.
+  # building for macOS, Windows or AIX, as those three platforms seemingly
+  # require it.
+  # On AIX, the tool chain doesn't support modifying rpaths/libpaths for XCOFF
+  # on install at the moment, so BUILD_WITH_INSTALL_RPATH is required.
   if("${CMAKE_BUILD_RPATH}" STREQUAL "")
-    if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin|Windows")
+    if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin|Windows|AIX")
       set_property(TARGET ${name} PROPERTY BUILD_WITH_INSTALL_RPATH ON)
     else()
       set_property(TARGET ${name} APPEND PROPERTY BUILD_RPATH "${_build_rpath}")