diff --git a/build-compiler-rt.sh b/build-compiler-rt.sh
index daa9d08..c5ecf0a 100755
--- a/build-compiler-rt.sh
+++ b/build-compiler-rt.sh
@@ -102,6 +102,7 @@ for arch in $ARCHS; do
         ;;
     esac
 
+    [ -z "$CLEAN" ] || rm -rf build-$arch$BUILD_SUFFIX
     mkdir -p build-$arch$BUILD_SUFFIX
     cd build-$arch$BUILD_SUFFIX
     cmake \
diff --git a/build-libcxx.sh b/build-libcxx.sh
index 9cb33f5..b4f1a9b 100755
--- a/build-libcxx.sh
+++ b/build-libcxx.sh
@@ -84,6 +84,7 @@ build_all() {
 
     cd libunwind
     for arch in $ARCHS; do
+        [ -z "$CLEAN" ] || rm -rf build-$arch-$type
         mkdir -p build-$arch-$type
         cd build-$arch-$type
         # CXX_SUPPORTS_CXX11 is not strictly necessary here. But if building
@@ -125,6 +126,7 @@ build_all() {
 
     cd libcxxabi
     for arch in $ARCHS; do
+        [ -z "$CLEAN" ] || rm -rf build-$arch-$type
         mkdir -p build-$arch-$type
         cd build-$arch-$type
         if [ "$type" = "shared" ]; then
@@ -163,6 +165,7 @@ build_all() {
 
     cd libcxx
     for arch in $ARCHS; do
+        [ -z "$CLEAN" ] || rm -rf build-$arch-$type
         mkdir -p build-$arch-$type
         cd build-$arch-$type
         if [ "$type" = "shared" ]; then
diff --git a/build-libssp.sh b/build-libssp.sh
index 1467ed9..b5b9e19 100755
--- a/build-libssp.sh
+++ b/build-libssp.sh
@@ -59,6 +59,7 @@ done
 cat ssp/ssp.h.in | sed 's/@ssp_have_usable_vsnprintf@/define/' > ssp/ssp.h
 
 for arch in $ARCHS; do
+    [ -z "$CLEAN" ] || rm -rf build-$arch
     mkdir -p build-$arch
     cd build-$arch
     $MAKE -f ../Makefile -j$CORES CROSS=$arch-w64-mingw32-
diff --git a/build-llvm.sh b/build-llvm.sh
index a0cc314..4d736f7 100755
--- a/build-llvm.sh
+++ b/build-llvm.sh
@@ -159,6 +159,7 @@ MINGW*)
     ;;
 esac
 
+[ -z "$CLEAN" ] || rm -rf $BUILDDIR
 mkdir -p $BUILDDIR
 cd $BUILDDIR
 # Building LLDB for macOS fails unless building libc++ is enabled at the
diff --git a/build-mingw-w64-libraries.sh b/build-mingw-w64-libraries.sh
index 528ffd2..0651a22 100755
--- a/build-mingw-w64-libraries.sh
+++ b/build-mingw-w64-libraries.sh
@@ -34,6 +34,7 @@ cd mingw-w64/mingw-w64-libraries
 for lib in winpthreads winstorecompat; do
     cd $lib
     for arch in $ARCHS; do
+        [ -z "$CLEAN" ] || rm -rf build-$arch
         mkdir -p build-$arch
         cd build-$arch
         ../configure --host=$arch-w64-mingw32 --prefix="$PREFIX/$arch-w64-mingw32" --libdir="$PREFIX/$arch-w64-mingw32/lib"
diff --git a/build-mingw-w64.sh b/build-mingw-w64.sh
index 502fe7d..3be0f9f 100755
--- a/build-mingw-w64.sh
+++ b/build-mingw-w64.sh
@@ -91,6 +91,7 @@ if [ -z "$HOST" ]; then
     fi
 
     cd mingw-w64-headers
+    [ -z "$CLEAN" ] || rm -rf build
     mkdir -p build
     cd build
     ../configure --prefix="$HEADER_ROOT" \
@@ -108,6 +109,7 @@ if [ -z "$HOST" ]; then
 
     cd mingw-w64-crt
     for arch in $ARCHS; do
+        [ -z "$CLEAN" ] || rm -rf build-$arch
         mkdir -p build-$arch
         cd build-$arch
         case $arch in
@@ -160,6 +162,7 @@ fi
 export PATH="$ORIGPATH"
 cd mingw-w64-tools/widl
 for arch in $ARCHS; do
+    [ -z "$CLEAN" ] || rm -rf build-$CROSS_NAME$arch
     mkdir -p build-$CROSS_NAME$arch
     cd build-$CROSS_NAME$arch
     ../configure --prefix="$PREFIX" --target=$arch-w64-mingw32 $CONFIGFLAGS
diff --git a/run-tests.sh b/run-tests.sh
index bde53d8..37e20ad 100755
--- a/run-tests.sh
+++ b/run-tests.sh
@@ -91,6 +91,7 @@ for arch in $ARCHS; do
     esac
 
     TEST_DIR="$arch"
+    [ -z "$CLEAN" ] || rm -rf $TEST_DIR
     mkdir -p $TEST_DIR
     for test in $TESTS_C; do
         $arch-w64-mingw32-clang $test.c -o $TEST_DIR/$test.exe