diff -r f617e60efe6f make/RunTests.gmk
--- a/make/RunTests.gmk	Wed May 20 14:30:28 2020 -0700
+++ b/make/RunTests.gmk	Mon Jun 15 09:08:34 2020 -0700
@@ -859,10 +859,14 @@
     $1_JTREG_LAUNCHER_OPTIONS += -Xmx$$($1_JTREG_MAX_MEM)
   endif
 
+  # Make sure the tmp dir is normalized as some tests will react badly otherwise
+  $1_TEST_TMP_DIR := $$(abspath $$($1_TEST_SUPPORT_DIR)/tmp)
+
   $1_JTREG_BASIC_OPTIONS += -$$($1_JTREG_TEST_MODE) \
       -verbose:$$(JTREG_VERBOSE) -retain:$$(JTREG_RETAIN) \
       -concurrency:$$($1_JTREG_JOBS) -timeoutFactor:$$(JTREG_TIMEOUT_FACTOR) \
-      -vmoption:-XX:MaxRAMPercentage=$$($1_JTREG_MAX_RAM_PERCENTAGE)
+      -vmoption:-XX:MaxRAMPercentage=$$($1_JTREG_MAX_RAM_PERCENTAGE) \
+      -vmoption:-Djava.io.tmpdir="$$($1_TEST_TMP_DIR)"
 
   $1_JTREG_BASIC_OPTIONS += -automatic -ignore:quiet
 
@@ -978,7 +982,8 @@
   run-test-$1: pre-run-test clean-workdir-$1 $$($1_AOT_TARGETS)
 	$$(call LogWarn)
 	$$(call LogWarn, Running test '$$($1_TEST)')
-	$$(call MakeDir, $$($1_TEST_RESULTS_DIR) $$($1_TEST_SUPPORT_DIR))
+	$$(call MakeDir, $$($1_TEST_RESULTS_DIR) $$($1_TEST_SUPPORT_DIR) \
+	    $$($1_TEST_TMP_DIR))
 	$$(call ExecuteWithLog, $$($1_TEST_SUPPORT_DIR)/jtreg, ( \
             $$(COV_ENVIRONMENT) $$($1_COMMAND_LINE) \
 	))