diff --git a/compiler-rt/cmake/Modules/CompilerRTMockLLVMCMakeConfig.cmake b/compiler-rt/cmake/Modules/CompilerRTMockLLVMCMakeConfig.cmake
new file mode 100644
--- /dev/null
+++ b/compiler-rt/cmake/Modules/CompilerRTMockLLVMCMakeConfig.cmake
@@ -0,0 +1,75 @@
+# This macro mocks enough of the changes `LLVMConfig.cmake` makes so that
+# compiler-rt can successfully configure itself when a LLVM toolchain is
+# available but the corresponding CMake build files are not.
+#
+# The motivation for this is to be able to generate the compiler-rt
+# lit tests suites and run them against an arbitrary LLVM toolchain
+# which doesn't ship the LLVM CMake build files.
+macro(compiler_rt_mock_llvm_cmake_config)
+  message(STATUS "Attempting to mock the changes made by LLVMConfig.cmake")
+  compiler_rt_mock_llvm_cmake_config_set_cmake_path()
+  compiler_rt_mock_llvm_cmake_config_set_target_triple()
+  compiler_rt_mock_llvm_cmake_config_include_cmake_files()
+endmacro()
+
+macro(compiler_rt_mock_llvm_cmake_config_set_cmake_path)
+  # Point `LLVM_CMAKE_PATH` at the source tree in the monorepo.
+  set(LLVM_CMAKE_PATH "${LLVM_MAIN_SRC_DIR}/cmake/modules")
+  if (NOT EXISTS "${LLVM_CMAKE_PATH}")
+    message(FATAL_ERROR "LLVM_CMAKE_PATH (${LLVM_CMAKE_PATH}) does not exist")
+  endif()
+  list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_PATH}")
+  message(STATUS "LLVM_CMAKE_PATH: \"${LLVM_CMAKE_PATH}\"")
+endmacro()
+
+function(compiler_rt_mock_llvm_cmake_config_set_target_triple)
+  # Various bits of compiler-rt depend on the `TARGET_TRIPLE`variable being
+  # defined. This function tries to set a sensible value for the variable.
+  # This is a function rather than a macro to avoid polluting the variable
+  # namespace.
+  set(COMPILER_OUTPUT "")
+
+  # If the user provides `COMPILER_RT_DEFAULT_TARGET_ONLY` and `CMAKE_C_COMPILER_TARGET`
+  # (see `construct_compiler_rt_default_triple`) then prefer that to examining the
+  # compiler.
+  if (COMPILER_RT_DEFAULT_TARGET_ONLY)
+    if (NOT "${CMAKE_C_COMPILER_TARGET}" STREQUAL "")
+      message(STATUS
+        "Using CMAKE_C_COMPILER_TARGET (${CMAKE_C_COMPILER_TARGET}) as TARGET_TRIPLE")
+    endif()
+    set(COMPILER_OUTPUT "${CMAKE_C_COMPILER_TARGET}")
+  endif()
+
+  # Try asking the compiler for its default target triple.
+  set(HAD_ERROR FALSE)
+  if ("${COMPILER_OUTPUT}" STREQUAL "")
+    if ("${CMAKE_C_COMPILER_ID}" MATCHES "Clang|GNU")
+      # Note: Clang also supports `-print-target-triple` but gcc doesn't
+      # support this flag.
+      execute_process(
+        COMMAND "${CMAKE_C_COMPILER}" -dumpmachine
+        RESULT_VARIABLE HAD_ERROR
+        OUTPUT_VARIABLE COMPILER_OUTPUT
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    else()
+      message(FATAL_ERROR
+        "Fetching target triple from compiler \"${CMAKE_C_COMPILER_ID}\" "
+        "is not implemented.")
+    endif()
+  endif()
+
+  if (HAD_ERROR)
+    message(FATAL_ERROR "Fetching target triple from compiler failed")
+  endif()
+  set(TARGET_TRIPLE "${COMPILER_OUTPUT}")
+  message(STATUS "TARGET_TRIPLE: \"${TARGET_TRIPLE}\"")
+  if ("${TARGET_TRIPLE}" STREQUAL "")
+    message(FATAL_ERROR "TARGET_TRIPLE cannot be empty")
+  endif()
+  set(TARGET_TRIPLE "${TARGET_TRIPLE}" PARENT_SCOPE)
+endfunction()
+
+macro(compiler_rt_mock_llvm_cmake_config_include_cmake_files)
+  # Some compiler-rt CMake code needs to call code in this file.
+  include("${LLVM_CMAKE_PATH}/AddLLVM.cmake")
+endmacro()
diff --git a/compiler-rt/cmake/Modules/CompilerRTUtils.cmake b/compiler-rt/cmake/Modules/CompilerRTUtils.cmake
--- a/compiler-rt/cmake/Modules/CompilerRTUtils.cmake
+++ b/compiler-rt/cmake/Modules/CompilerRTUtils.cmake
@@ -283,6 +283,7 @@
       "You are not using the monorepo layout. This configuration is DEPRECATED.")
   endif()
 
+  set(FOUND_LLVM_CMAKE_PATH FALSE)
   if (LLVM_CONFIG_PATH)
     execute_process(
       COMMAND ${LLVM_CONFIG_PATH} "--obj-root" "--bindir" "--libdir" "--src-root" "--includedir"
@@ -372,9 +373,15 @@
       set(LLVM_CMAKE_PATH "${LLVM_BINARY_DIR_CMAKE_STYLE}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm")
     endif()
 
-    list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_PATH}")
-    # Get some LLVM variables from LLVMConfig.
-    include("${LLVM_CMAKE_PATH}/LLVMConfig.cmake")
+    if (EXISTS "${LLVM_CMAKE_PATH}")
+      list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_PATH}")
+      # Get some LLVM variables from LLVMConfig.
+      include("${LLVM_CMAKE_PATH}/LLVMConfig.cmake")
+      set(FOUND_LLVM_CMAKE_PATH TRUE)
+    else()
+      set(FOUND_LLVM_CMAKE_PATH FALSE)
+      message(WARNING "LLVM CMake path (${LLVM_CMAKE_PATH}) reported by llvm-config does not exist")
+    endif()
 
     set(LLVM_LIBRARY_OUTPUT_INTDIR
       ${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
@@ -393,6 +400,15 @@
                     "the `llvm-project` repo. "
                     "This will be treated as error in the future.")
   endif()
+
+  if (NOT FOUND_LLVM_CMAKE_PATH)
+    # This configuration tries to configure without the prescence of `LLVMConfig.cmake`. It is
+    # intended for testing purposes (generating the lit test suites) and will likely not support
+    # a build of the runtimes in compiler-rt.
+    include(CompilerRTMockLLVMCMakeConfig)
+    compiler_rt_mock_llvm_cmake_config()
+  endif()
+
 endmacro()
 
 macro(construct_compiler_rt_default_triple)