Index: lib/Fuzzer/test/merge-posix.test
===================================================================
--- /dev/null
+++ lib/Fuzzer/test/merge-posix.test
@@ -0,0 +1,17 @@
+CHECK: BINGO
+
+RUN: rm -rf  %tmp/T1 %tmp/T2
+RUN: mkdir -p %tmp/T1 %tmp/T2
+RUN: echo F..... > %tmp/T1/1
+RUN: echo .U.... > %tmp/T1/2
+RUN: echo ..Z... > %tmp/T1/3
+
+# Check that we honor TMPDIR
+RUN: TMPDIR=DIR_DOES_NOT_EXIST not LLVMFuzzer-FullCoverageSetTest -merge=1 %tmp/T1 %tmp/T2 2>&1 | FileCheck %s --check-prefix=TMPDIR
+TMPDIR: MERGE-OUTER: failed to write to the control file: DIR_DOES_NOT_EXIST/libFuzzerTemp
+
+# Check that we can report an error if file size exceeded
+RUN: (ulimit -f 1; not LLVMFuzzer-FullCoverageSetTest -merge=1 %tmp/T1 %tmp/T2 2>&1 | FileCheck %s --check-prefix=SIGXFSZ)
+SIGXFSZ: ERROR: libFuzzer: file size exceeded
+
+REQUIRES: posix
Index: lib/Fuzzer/test/merge.test
===================================================================
--- lib/Fuzzer/test/merge.test
+++ lib/Fuzzer/test/merge.test
@@ -45,14 +45,6 @@
 RUN: LLVMFuzzer-FullCoverageSetTest -merge=1 %tmp/T1 %tmp/T2  -max_len=5 2>&1 | FileCheck %s --check-prefix=MERGE_LEN5
 MERGE_LEN5: MERGE-OUTER: succesfull in 1 attempt(s)
 
-# Check that we honor TMPDIR
-RUN: TMPDIR=DIR_DOES_NOT_EXIST not LLVMFuzzer-FullCoverageSetTest -merge=1 %tmp/T1 %tmp/T2 2>&1 | FileCheck %s --check-prefix=TMPDIR
-TMPDIR: MERGE-OUTER: failed to write to the control file: DIR_DOES_NOT_EXIST/libFuzzerTemp
-
-# Check that we can report an error if file size exceeded
-RUN: (ulimit -f 1; not LLVMFuzzer-FullCoverageSetTest -merge=1 %tmp/T1 %tmp/T2 2>&1 | FileCheck %s --check-prefix=SIGXFSZ)
-SIGXFSZ: ERROR: libFuzzer: file size exceeded
-
 RUN: rm -rf  %tmp/T1/* %tmp/T2/*
 RUN: not LLVMFuzzer-FullCoverageSetTest -merge=1 %tmp/T1 %tmp/T2 2>&1 | FileCheck %s --check-prefix=EMPTY
 EMPTY: MERGE-OUTER: zero succesfull attempts, exiting