diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index 9f814478c4550..5f2b7f064da43 100644
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -193,6 +193,12 @@ set(C_INCLUDE_DIRS "" CACHE STRING
 set(GCC_INSTALL_PREFIX "" CACHE PATH "Directory where gcc is installed." )
 set(DEFAULT_SYSROOT "" CACHE STRING
   "Default <path> to all compiler invocations for --sysroot=<path>." )
+if(GCC_INSTALL_PREFIX)
+  message(WARNING "GCC_INSTALL_PREFIX is deprecated and will be removed. Use "
+    "configuration files (https://clang.llvm.org/docs/UsersManual.html#configuration-files)"
+    "to specify the default --gcc-install-dir= or --gcc-triple=. --gcc-toolchain= is discouraged. "
+    "See https://github.com/llvm/llvm-project/pull/77537 for detail.")
+endif()
 
 set(ENABLE_LINKER_BUILD_ID OFF CACHE BOOL "pass --build-id to ld")
 
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index ddeb1186d65ac..101e018d51884 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -37,6 +37,12 @@ These changes are ones which we think may surprise users when upgrading to
 Clang |release| because of the opportunity they pose for disruption to existing
 code bases.
 
+- The CMake variable ``GCC_INSTALL_PREFIX`` (which sets the default
+  ``--gcc-toolchain=``) is deprecated and will be removed. Specify
+  ``--gcc-install-dir=`` or ``--gcc-triple=`` in a `configuration file
+  <https://clang.llvm.org/docs/UsersManual.html#configuration-files>` as a
+  replacement.
+  (`#77537 <https://github.com/llvm/llvm-project/pull/77537>`_)
 
 C/C++ Language Potentially Breaking Changes
 -------------------------------------------