diff --git a/gcc/d/Make-lang.in b/gcc/d/Make-lang.in
index a29531c8b7f685e3530ac52b35854275b4edd813..2d444c9995304dd180389c9eb9b486bc6f05d75d 100644
--- a/gcc/d/Make-lang.in
+++ b/gcc/d/Make-lang.in
@@ -308,7 +308,7 @@ d.srcman: doc/gdc.1
 check-d: check-gdc
 lang_checks += check-gdc
 lang_checks_parallelized += check-gdc
-check_gdc_parallelize = 10
+check_gdc_parallelize = 128
 
 # No D-specific selftests.
 selftest-d:
diff --git a/libphobos/testsuite/Makefile.am b/libphobos/testsuite/Makefile.am
index 54dc7ba540f75bdf8dff81fa8bda0c0d0fb90ee2..ecddb80db5df8ad38bae80136d9bea6da8c4ed58 100644
--- a/libphobos/testsuite/Makefile.am
+++ b/libphobos/testsuite/Makefile.am
@@ -29,7 +29,6 @@ RUNTESTDEFAULTFLAGS = --tool $$tool --srcdir $$srcdir
 
 PWD_COMMAND = $${PWDCMD-pwd}
 
-check_p_subno=$(word 2,$(subst _, ,$*))
 check_p_numbers0:=1 2 3 4 5 6 7 8 9
 check_p_numbers1:=0 $(check_p_numbers0)
 check_p_numbers2:=$(foreach i,$(check_p_numbers0),$(addprefix $(i),$(check_p_numbers1)))
@@ -38,7 +37,7 @@ check_p_numbers4:=$(foreach i,$(check_p_numbers0),$(addprefix $(i),$(check_p_num
 check_p_numbers5:=$(addprefix 0,$(check_p_numbers3)) $(check_p_numbers4)
 check_p_numbers6:=$(foreach i,$(check_p_numbers0),$(addprefix $(i),$(check_p_numbers5)))
 check_p_numbers:=$(check_p_numbers0) $(check_p_numbers2) $(check_p_numbers4) $(check_p_numbers6)
-check_p_subdirs=$(wordlist 1,$(if $(GCC_TEST_PARALLEL_SLOTS),$(GCC_TEST_PARALLEL_SLOTS),10),$(check_p_numbers))
+check_p_subdirs=$(wordlist 1,$(if $(GCC_TEST_PARALLEL_SLOTS),$(GCC_TEST_PARALLEL_SLOTS),128),$(check_p_numbers))
 check_DEJAGNU_libphobos_targets = $(addprefix check-DEJAGNUlibphobos,$(check_p_subdirs))
 $(check_DEJAGNU_libphobos_targets): check-DEJAGNUlibphobos%: libphobos%/site.exp
 
diff --git a/libphobos/testsuite/Makefile.in b/libphobos/testsuite/Makefile.in
index 885548018baeea8997471889c9c9c12d60c486ee..3d3a798f35c10b0bafef68e2a9a25686120ebcd3 100644
--- a/libphobos/testsuite/Makefile.in
+++ b/libphobos/testsuite/Makefile.in
@@ -301,7 +301,6 @@ _RUNTEST = $(shell if test -f $(top_srcdir)/../dejagnu/runtest; then \
 
 RUNTESTDEFAULTFLAGS = --tool $$tool --srcdir $$srcdir
 PWD_COMMAND = $${PWDCMD-pwd}
-check_p_subno = $(word 2,$(subst _, ,$*))
 check_p_numbers0 := 1 2 3 4 5 6 7 8 9
 check_p_numbers1 := 0 $(check_p_numbers0)
 check_p_numbers2 := $(foreach i,$(check_p_numbers0),$(addprefix $(i),$(check_p_numbers1)))
@@ -310,7 +309,7 @@ check_p_numbers4 := $(foreach i,$(check_p_numbers0),$(addprefix $(i),$(check_p_n
 check_p_numbers5 := $(addprefix 0,$(check_p_numbers3)) $(check_p_numbers4)
 check_p_numbers6 := $(foreach i,$(check_p_numbers0),$(addprefix $(i),$(check_p_numbers5)))
 check_p_numbers := $(check_p_numbers0) $(check_p_numbers2) $(check_p_numbers4) $(check_p_numbers6)
-check_p_subdirs = $(wordlist 1,$(if $(GCC_TEST_PARALLEL_SLOTS),$(GCC_TEST_PARALLEL_SLOTS),10),$(check_p_numbers))
+check_p_subdirs = $(wordlist 1,$(if $(GCC_TEST_PARALLEL_SLOTS),$(GCC_TEST_PARALLEL_SLOTS),128),$(check_p_numbers))
 check_DEJAGNU_libphobos_targets = $(addprefix check-DEJAGNUlibphobos,$(check_p_subdirs))
 AM_MAKEFLAGS = "EXEEXT=$(EXEEXT)"
 CLEANFILES = *.exe *.log *.o *.sum site.exp