Index: lldb/cmake/modules/LLDBConfig.cmake
===================================================================
--- lldb/cmake/modules/LLDBConfig.cmake
+++ lldb/cmake/modules/LLDBConfig.cmake
@@ -250,6 +250,30 @@
   endif()
 endif()
 
+
+# If LLDB is building against a prebuilt Clang, then the Clang resource
+# directory that LLDB is using for its embedded Clang instance needs to point
+# to the resource directory of the used Clang installation.
+if (NOT TARGET clang-resource-headers)
+  set(LLDB_CLANG_RESOURCE_DIR_NAME "${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
+  # Iterate over the possible places where the external resource directory
+  # could be and pick the first that exists.
+  foreach(CANDIDATE "${Clang_DIR}/../.." "${LLVM_DIR}" "${LLVM_LIBRARY_DIRS}"
+                    "${LLVM_BUILD_LIBRARY_DIR}"
+                    "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}")
+    # Build the resource directory path by appending 'clang/<version number>'.
+    set(CANDIDATE_RESOURCE_DIR "${CANDIDATE}/clang/${LLDB_CLANG_RESOURCE_DIR_NAME}")
+    if (IS_DIRECTORY "${CANDIDATE_RESOURCE_DIR}")
+      set(LLDB_EXTERNAL_CLANG_RESOURCE_DIR "${CANDIDATE_RESOURCE_DIR}")
+      break()
+    endif()
+  endforeach()
+
+  if (NOT LLDB_EXTERNAL_CLANG_RESOURCE_DIR)
+    message(FATAL_ERROR "Expected directory for clang-resource headers not found: ${LLDB_EXTERNAL_CLANG_RESOURCE_DIR}")
+  endif()
+endif()
+
 # Find Apple-specific libraries or frameworks that may be needed.
 if (APPLE)
   if(NOT APPLE_EMBEDDED)
Index: lldb/cmake/modules/LLDBFramework.cmake
===================================================================
--- lldb/cmake/modules/LLDBFramework.cmake
+++ lldb/cmake/modules/LLDBFramework.cmake
@@ -110,20 +110,7 @@
     add_dependencies(liblldb clang-resource-headers)
     set(clang_resource_headers_dir $<TARGET_PROPERTY:clang-resource-headers,RUNTIME_OUTPUT_DIRECTORY>)
   else()
-    # In standalone builds try the best possible guess
-    if(Clang_DIR)
-      set(clang_lib_dir ${Clang_DIR}/../..)
-    elseif(LLVM_DIR)
-      set(clang_lib_dir ${LLVM_DIR}/../..)
-    elseif(LLVM_LIBRARY_DIRS)
-      set(clang_lib_dir ${LLVM_LIBRARY_DIRS})
-    elseif(LLVM_BUILD_LIBRARY_DIR)
-      set(clang_lib_dir ${LLVM_BUILD_LIBRARY_DIR})
-    elseif(LLVM_BINARY_DIR)
-      set(clang_lib_dir ${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
-    endif()
-    set(clang_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH})
-    set(clang_resource_headers_dir ${clang_lib_dir}/clang/${clang_version}/include)
+    set(clang_resource_headers_dir ${LLDB_EXTERNAL_CLANG_RESOURCE_DIR}/include)
     if(NOT EXISTS ${clang_resource_headers_dir})
       message(WARNING "Expected directory for clang-resource headers not found: ${clang_resource_headers_dir}")
     endif()
Index: lldb/source/API/CMakeLists.txt
===================================================================
--- lldb/source/API/CMakeLists.txt
+++ lldb/source/API/CMakeLists.txt
@@ -195,8 +195,27 @@
   )
 endif()
 
-if (NOT LLDB_BUILT_STANDALONE)
+# The Clang expression parser in LLDB requires the Clang resource directory to function.
+if (TARGET clang-resource-headers)
+  # If building alongside Clang, just add a dependency to ensure it is build together with liblldb.
   add_dependencies(liblldb clang-resource-headers)
+else()
+  # In a standalone build create a symlink from the LLDB library directory that points to the
+  # resource directory in the Clang library directory. LLDB searches relative to its install path,
+  # and the symlink is created in the same relative path as the resource directory of Clang when
+  # building alongside Clang.
+  # When building the LLDB framework, this isn't necessary as there we copy everything we need into
+  # the framework (including the Clang resourece directory).
+  if(NOT LLDB_BUILD_FRAMEWORK)
+    set(LLDB_CLANG_RESOURCE_DIR_PARENT "$<TARGET_FILE_DIR:liblldb>/clang")
+    file(MAKE_DIRECTORY "${LLDB_CLANG_RESOURCE_DIR_PARENT}")
+    add_custom_command(TARGET liblldb POST_BUILD
+      COMMENT "Linking Clang resource dir into LLDB build directory: ${LLDB_CLANG_RESOURCE_DIR_PARENT}"
+      COMMAND ${CMAKE_COMMAND} -E make_directory "${LLDB_CLANG_RESOURCE_DIR_PARENT}"
+      COMMAND ${CMAKE_COMMAND} -E create_symlink "${LLDB_EXTERNAL_CLANG_RESOURCE_DIR}"
+              "${LLDB_CLANG_RESOURCE_DIR_PARENT}/${LLDB_CLANG_RESOURCE_DIR_NAME}"
+    )
+  endif()
 endif()
 
 if(LLDB_BUILD_FRAMEWORK)