diff --git a/pkgs/build-support/clang-wrapper/clang-wrapper.sh b/pkgs/build-support/clang-wrapper/clang-wrapper.sh
index 2052d2c2eb4..4f710856868 100644
--- a/pkgs/build-support/clang-wrapper/clang-wrapper.sh
+++ b/pkgs/build-support/clang-wrapper/clang-wrapper.sh
@@ -134,6 +134,12 @@ if test -n "$NIX_CLANG_WRAPPER_EXEC_HOOK"; then
     source "$NIX_CLANG_WRAPPER_EXEC_HOOK"
 fi
 
+# We nuke LD_LIBRARY_PATH here, because clang dynamically links to LLVM.
+# Unfortunately, when such clang is used to build LLVM again, it can get in
+# trouble temporarily binding to the build-directory versions of the libraries
+# (the buildsystem sets LD_LIBRARY_PATH).  That is very undesirable and can
+# cause mysterious failures.
+LD_LIBRARY_PATH=
 
 # Call the real `clang'.  Filter out warnings from stderr about unused
 # `-B' flags, since they confuse some programs.  Deep bash magic to