diff --git a/Changes b/Changes
index 6131b50de..2099d9d85 100644
--- a/Changes
+++ b/Changes
@@ -5,6 +5,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 * Verilator 4.031 devel
 
+***   Add setting VM_PARALLEL_BUILDS=1 when using --output-split, #2185.
+
 
 * Verilator 4.030 2020-03-08
 
diff --git a/bin/verilator b/bin/verilator
index b321db9e7..79a9ffd59 100755
--- a/bin/verilator
+++ b/bin/verilator
@@ -1083,8 +1083,8 @@ and the remaining files can be compiled on parallel machines.  Using
 design --output-split 20000 resulted in splitting into approximately
 one-minute-compile chunks.
 
-Typically when using this, make with VM_PARALLEL_BUILDS=1, and use
-I<ccache>.
+Typically when using this, make with VM_PARALLEL_BUILDS=1 (set for you if
+using the default makefiles), and use I<ccache>.
 
 =item --output-split-cfuncs I<statements>
 
diff --git a/src/V3EmitMk.cpp b/src/V3EmitMk.cpp
index c8a83ce2a..fbb899c09 100644
--- a/src/V3EmitMk.cpp
+++ b/src/V3EmitMk.cpp
@@ -51,6 +51,9 @@ public:
         of.puts("\n### Switches...\n");
         of.puts("# Coverage output mode?  0/1 (from --coverage)\n");
         of.puts("VM_COVERAGE = "); of.puts(v3Global.opt.coverage()?"1":"0"); of.puts("\n");
+        of.puts("# Parallel builds?  0/1 (from --output-split)\n");
+        of.puts("VM_PARALLEL_BUILDS = ");
+        of.puts(v3Global.opt.outputSplit() ? "1" : "0"); of.puts("\n");
         of.puts("# Threaded output mode?  0/1/N threads (from --threads)\n");
         of.puts("VM_THREADS = "); of.puts(cvtToStr(v3Global.opt.threads())); of.puts("\n");
         of.puts("# Tracing output mode?  0/1 (from --trace)\n");
diff --git a/test_regress/t/t_flag_csplit.pl b/test_regress/t/t_flag_csplit.pl
index 4d08bb271..77b7ece65 100755
--- a/test_regress/t/t_flag_csplit.pl
+++ b/test_regress/t/t_flag_csplit.pl
@@ -31,7 +31,7 @@ while (1) {
               "-C ".$Self->{obj_dir},
               "-f $Self->{VM_PREFIX}.mk",
               "-j 4",
-              "VM_PARALLEL_BUILDS=1",  # Important to this test
+              #"VM_PARALLEL_BUILDS=1",  # Check is set by makefile
               "VM_PREFIX=$Self->{VM_PREFIX}",
               "TEST_OBJ_DIR=$Self->{obj_dir}",
               "CPPFLAGS_DRIVER=-D".uc($Self->{name}),