diff --git a/debian/changelog b/debian/changelog
index cd0c051c..84219be6 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -156,6 +156,15 @@ llvm-toolchain-snapshot (1:13~++20210129063721+010b176cdefb-1~exp1) experimental
 
  -- Sylvestre Ledru <sylvestre@debian.org>  Sat, 30 Jan 2021 17:31:15 +0100
 
+llvm-toolchain-12 (1:12.0.1-10) UNRELEASED; urgency=medium
+
+  * If parallel is not set in DEB_BUILD_OPTIONS, use nproc
+
+  [ John Paul Adrian Glaubitz ]
+  * Disable libunwind on sparc, sparc64 and x32
+
+ -- Sylvestre Ledru <sylvestre@debian.org>  Sat, 02 Oct 2021 10:50:27 +0200
+
 llvm-toolchain-12 (1:12.0.1-9) unstable; urgency=medium
 
   * Replace make by ninja for the build process
diff --git a/debian/rules b/debian/rules
index 60791e4a..805f41ad 100755
--- a/debian/rules
+++ b/debian/rules
@@ -28,6 +28,8 @@ SONAME_OPENMP	:= 5
 DEBIAN_REVISION := $(shell dpkg-parsechangelog |  sed -rne "s,^Version: 1:([0-9.]+)(~|-)(.*),\3,p")
 ifneq (,$(filter parallel=%,$(subst $(COMMA), ,$(DEB_BUILD_OPTIONS))))
   NJOBS := -j $(subst parallel=,,$(filter parallel=%,$(subst $(COMMA), ,$(DEB_BUILD_OPTIONS))))
+else
+  NJOBS := $(shell nproc)
 endif
 
 VENDOR=$(shell lsb_release -is)
@@ -205,7 +207,7 @@ endif
 
 # Enable libunwind (or not)
 LIBUNWIND_ENABLE=yes
-ifneq (,$(filter $(DEB_HOST_ARCH), s390x armel m68k mipsel hurd-i386 powerpc sparc64 x32))
+ifneq (,$(filter $(DEB_HOST_ARCH), s390x armel m68k mipsel hurd-i386 powerpc sparc sparc64 x32))
   LIBUNWIND_ENABLE=no
 else
   PROJECTS += ;libunwind
@@ -453,13 +455,8 @@ override_dh_auto_configure: preconfigure
 	fi
 
 
-ifeq (Ninja, $(GENERATOR))
 # ninja
 VERBOSE=-v
-else
-# make
-VERBOSE=VERBOSE=1
-endif
 
 debian-full-build:
 	$(PRE_PROCESS) ninja $(NJOBS) -C $(TARGET_BUILD) $(VERBOSE) stage2
@@ -590,13 +587,13 @@ build_doc:
 	cd $(CURDIR)/llvm/docs && make -f Makefile.sphinx && make -f Makefile.sphinx man
 	cd $(CURDIR)/clang/docs && make -f Makefile.sphinx && make -f Makefile.sphinx man
 	-(if test "$(OCAML_ENABLE)" = yes; then \
-	ninja -C "$(TARGET_BUILD_STAGE2)" ocaml_doc $(VERBOSE); \
+	ninja -C "$(TARGET_BUILD_STAGE2)" $(VERBOSE) ocaml_doc; \
 	fi)
 
-	ninja -C $(TARGET_BUILD_STAGE2) docs-llvm-html docs-clang-html docs-clang-tools-html docs-clang-tools-man docs-clang-man docs-llvm-man $(VERBOSE)
+	ninja -C $(TARGET_BUILD_STAGE2) $(VERBOSE) docs-llvm-html docs-clang-html docs-clang-tools-html docs-clang-tools-man docs-clang-man docs-llvm-man
 
 ifeq (${POLLY_ENABLE},yes)
-	ninja -C $(TARGET_BUILD_STAGE2) docs-polly-html docs-polly-man $(VERBOSE)
+	ninja -C $(TARGET_BUILD_STAGE2) $(VERBOSE) docs-polly-html docs-polly-man
 endif
 
 # Rename manpages
@@ -715,9 +712,9 @@ endif
 	rm -rf $(DEB_INST)/usr/lib/llvm-$(LLVM_VERSION)/build/utils/lit/lit/__pycache__/ \
 	$(DEB_INST)/usr/lib/llvm-$(LLVM_VERSION)/build/utils/lit/lit/*/__pycache__/
 
-	DESTDIR=$(DEB_INST) ninja -C libcxxabi/build install $(VERBOSE)
-	DESTDIR=$(DEB_INST) ninja -C libcxx/build install $(VERBOSE)
-	DESTDIR=$(DEB_INST) ninja -C libclc/build install $(VERBOSE)
+	DESTDIR=$(DEB_INST) ninja $(VERBOSE) -C libcxxabi/build install
+	DESTDIR=$(DEB_INST) ninja $(VERBOSE) -C libcxx/build install
+	DESTDIR=$(DEB_INST) ninja $(VERBOSE) -C libclc/build install
 
 # Rename binaries
 	mkdir -p $(DEB_INST)/usr/bin/
@@ -892,33 +889,33 @@ override_dh_auto_test:
 # LLVM tests
 ifneq (,$(findstring $(DEB_HOST_ARCH),$(ARCH_LLVM_TEST_OK)))
 # logs the output to check-llvm_build_log.txt for validation through autopkgtest
-	ninja -C $(TARGET_BUILD) stage2-check-llvm | tee check-llvm_build_log.txt
+	ninja $(VERBOSE) -C $(TARGET_BUILD) stage2-check-llvm | tee check-llvm_build_log.txt
 else
-	ninja -C $(TARGET_BUILD) stage2-check-llvm || true
+	ninja $(VERBOSE) -C $(TARGET_BUILD) stage2-check-llvm || true
 endif
 
 # Clang tests
-	ninja -C $(TARGET_BUILD) stage2-check-clang || true
+	ninja $(VERBOSE) -C $(TARGET_BUILD) stage2-check-clang || true
 
 # Clang extra tests (ex: clang-tidy)
-	ninja -C $(TARGET_BUILD_STAGE2) check-clang-tools || true
+	ninja $(VERBOSE) -C $(TARGET_BUILD_STAGE2) check-clang-tools || true
 
 # LLD tests
 ifeq (${LLD_ENABLE},yes)
-	ninja -C $(TARGET_BUILD_STAGE2) check-lld || true
+	ninja $(VERBOSE) -C $(TARGET_BUILD_STAGE2) check-lld || true
 endif
 
 # Sanitizer
-	ninja -C $(TARGET_BUILD_STAGE2) check-sanitizer || true
+	ninja $(VERBOSE) -C $(TARGET_BUILD_STAGE2) check-sanitizer || true
 
 # Libcxx
-	ninja -C libcxx/build check-libcxx || true
+	ninja $(VERBOSE) -C libcxx/build check-libcxx || true
 
 # Libcxxabi
-	ninja -C libcxxabi/build check-libcxxabi || true
+	ninja $(VERBOSE) -C libcxxabi/build check-libcxxabi || true
 
 # Libclc
-	ninja -C libclc/build test || true
+	ninja $(VERBOSE) -C libclc/build test || true
 
 # LLDB tests
 ifeq (,$(filter $(DEB_HOST_ARCH), $(LLDB_DISABLE_ARCHS) armhf armel))
@@ -929,7 +926,7 @@ ifneq (,$(filter codecoverage,$(DEB_BUILD_OPTIONS)))
 			ln -s lldb/_lldb.so; \
 		fi
 	if test "$(CODECOVERAGE)" = "no"; then \
-	LD_LIBRARY_PATH=$$LD_LIBRARY_PATH:$(CURDIR)/$(TARGET_BUILD)/lib/ ninja -C $(TARGET_BUILD) check-lldb || true; \
+	LD_LIBRARY_PATH=$$LD_LIBRARY_PATH:$(CURDIR)/$(TARGET_BUILD)/lib/ ninja $(VERBOSE) -C $(TARGET_BUILD) check-lldb || true; \
 	fi
 	# remove the workaround
 	rm $(CURDIR)/$(TARGET_BUILD)/lib/python*/*-packages/_lldb.so