diff --git a/ep/build-velox/src/build-velox.sh b/ep/build-velox/src/build-velox.sh
index 31109ed919..3e279bf680 100755
--- a/ep/build-velox/src/build-velox.sh
+++ b/ep/build-velox/src/build-velox.sh
@@ -115,9 +115,12 @@ function compile {
   if [[ "$(uname)" == "Darwin" ]]; then
     CXX_FLAGS="$CXX_FLAGS -Wno-inconsistent-missing-override -Wno-macro-redefined"
     if [[ -n "${INSTALL_PREFIX:-}" && "${INSTALL_PREFIX:-}" != "/usr/local" && "${INSTALL_PREFIX:-}" != /usr/local/* ]]; then
-      # Some prefix-installed deps only publish loose headers (e.g. xsimd), so
-      # keep the prefix include dir on the compiler command line.
-      CXX_FLAGS="$CXX_FLAGS -I${INSTALL_PREFIX}/include"
+      # Add the dependency prefix as a system include: this finds deps that only
+      # publish loose headers (e.g. xsimd) and demotes warnings in vendored
+      # dependency headers (abseil's __is_trivially_relocatable, arrow's vendored
+      # date.h literal operators) to non-fatal system-header warnings under
+      # -Werror on recent clang.
+      CXX_FLAGS="$CXX_FLAGS -isystem ${INSTALL_PREFIX}/include"
     fi
   fi