diff --git a/compiler-rt/lib/fuzzer/FuzzerIOWindows.cpp b/compiler-rt/lib/fuzzer/FuzzerIOWindows.cpp
index 314b79d0f81bc..75dcaf72a9402 100644
--- a/compiler-rt/lib/fuzzer/FuzzerIOWindows.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerIOWindows.cpp
@@ -111,7 +111,7 @@ void ListFilesInDirRecursive(const std::string &Dir, long *Epoch,
   {
     if (GetLastError() == ERROR_FILE_NOT_FOUND)
       return;
-    Printf("No such directory: %s; exiting\n", Dir.c_str());
+    Printf("No such file or directory: %s; exiting\n", Dir.c_str());
     exit(1);
   }
 
diff --git a/compiler-rt/test/CMakeLists.txt b/compiler-rt/test/CMakeLists.txt
index 0a3fc025419ca..554ba5fa0f0eb 100644
--- a/compiler-rt/test/CMakeLists.txt
+++ b/compiler-rt/test/CMakeLists.txt
@@ -62,10 +62,7 @@ if(COMPILER_RT_CAN_EXECUTE_TESTS)
     compiler_rt_test_runtime(sanitizer_common)
 
     # OpenBSD not supporting asan, cannot run the tests
-    # Tests are broken for now on Windows
-    if(COMPILER_RT_BUILD_LIBFUZZER
-      AND NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "OpenBSD"
-      AND NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "Windows" AND NOT ANDROID)
+    if(COMPILER_RT_BUILD_LIBFUZZER AND NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "OpenBSD" AND NOT ANDROID)
       compiler_rt_test_runtime(fuzzer)
     endif()
 
diff --git a/compiler-rt/test/fuzzer/afl-driver-extra-stats.test b/compiler-rt/test/fuzzer/afl-driver-extra-stats.test
index cddb683e6dec5..2f5641daf7245 100644
--- a/compiler-rt/test/fuzzer/afl-driver-extra-stats.test
+++ b/compiler-rt/test/fuzzer/afl-driver-extra-stats.test
@@ -1,3 +1,5 @@
+# AFL doesn't work on Windows. No reason to test the driver.
+UNSUPPORTED: windows
 XFAIL: ios
 RUN: %no_fuzzer_cpp_compiler %S/AFLDriverTest.cpp %libfuzzer_src/afl/afl_driver.cpp -o %t-AFLDriverTest
 
diff --git a/compiler-rt/test/fuzzer/afl-driver-stderr.test b/compiler-rt/test/fuzzer/afl-driver-stderr.test
index d3d739d3b977e..5e3007e5427ee 100644
--- a/compiler-rt/test/fuzzer/afl-driver-stderr.test
+++ b/compiler-rt/test/fuzzer/afl-driver-stderr.test
@@ -1,5 +1,6 @@
+# AFL doesn't work on Windows. No reason to test the driver.
+UNSUPPORTED: freebsd, windows
 XFAIL: ios
-UNSUPPORTED: freebsd
 RUN: %no_fuzzer_cpp_compiler %S/AFLDriverTest.cpp %libfuzzer_src/afl/afl_driver.cpp -o %t-AFLDriverTest
 
 ; Test that not specifying a stderr file isn't broken.
diff --git a/compiler-rt/test/fuzzer/bogus-initialize.test b/compiler-rt/test/fuzzer/bogus-initialize.test
index 2dff2d5a26395..69cebb614ecff 100644
--- a/compiler-rt/test/fuzzer/bogus-initialize.test
+++ b/compiler-rt/test/fuzzer/bogus-initialize.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows since LLVMFuzzerInitialize does not yet work.
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/BogusInitializeTest.cpp -o %t-BogusInitializeTest
 
 RUN: not %run %t-BogusInitializeTest 2>&1 | FileCheck %s --check-prefix=BOGUS_INITIALIZE
diff --git a/compiler-rt/test/fuzzer/coverage.test b/compiler-rt/test/fuzzer/coverage.test
index 3b2341f21f695..12a91c8ca8bd7 100644
--- a/compiler-rt/test/fuzzer/coverage.test
+++ b/compiler-rt/test/fuzzer/coverage.test
@@ -1,4 +1,5 @@
-UNSUPPORTED: aarch64
+# FIXME: Disabled on Windows because -fPIC cannot be used to compile for Windows.
+UNSUPPORTED: aarch64, windows
 RUN: %cpp_compiler -mllvm -use-unknown-locations=Disable  %S/NullDerefTest.cpp -o %t-NullDerefTest
 RUN: %cpp_compiler -mllvm -use-unknown-locations=Disable %S/DSO1.cpp -fPIC %ld_flags_rpath_so1 -shared -o %dynamiclib1
 RUN: %cpp_compiler -mllvm -use-unknown-locations=Disable %S/DSO2.cpp -fPIC %ld_flags_rpath_so2 -shared -o %dynamiclib2
diff --git a/compiler-rt/test/fuzzer/dso.test b/compiler-rt/test/fuzzer/dso.test
index fc1fe23818f04..60ef8a6ac8323 100644
--- a/compiler-rt/test/fuzzer/dso.test
+++ b/compiler-rt/test/fuzzer/dso.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows because -fPIC cannot be used to compile for Windows.
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/DSO1.cpp -fPIC %ld_flags_rpath_so1 -shared -o %dynamiclib1
 RUN: %cpp_compiler %S/DSO2.cpp -fPIC %ld_flags_rpath_so2 -shared -o %dynamiclib2
 RUN: %cpp_compiler %S/DSOTestMain.cpp %S/DSOTestExtra.cpp %ld_flags_rpath_exe1 %ld_flags_rpath_exe2 -o %t-DSOTest
diff --git a/compiler-rt/test/fuzzer/dump_coverage.test b/compiler-rt/test/fuzzer/dump_coverage.test
index 41e193824de6a..21e4348f1cefe 100644
--- a/compiler-rt/test/fuzzer/dump_coverage.test
+++ b/compiler-rt/test/fuzzer/dump_coverage.test
@@ -1,4 +1,5 @@
-UNSUPPORTED: freebsd
+# FIXME: Disabled on Windows because -fPIC cannot be used to compile for Windows.
+UNSUPPORTED: freebsd, windows
 RUN: %cpp_compiler -fsanitize-coverage=0 -fsanitize-coverage=trace-pc-guard %S/DSO1.cpp -fPIC -shared -o %dynamiclib1 %ld_flags_rpath_so1
 RUN: %cpp_compiler -fsanitize-coverage=0 -fsanitize-coverage=trace-pc-guard %S/DSO2.cpp -fPIC -shared -o %dynamiclib2 %ld_flags_rpath_so2
 RUN: %cpp_compiler -fsanitize-coverage=0 -fsanitize-coverage=trace-pc-guard %S/DSOTestMain.cpp %S/DSOTestExtra.cpp %ld_flags_rpath_exe1 %ld_flags_rpath_exe2 -o %t-DSOTest
diff --git a/compiler-rt/test/fuzzer/exit_on_src_pos.test b/compiler-rt/test/fuzzer/exit_on_src_pos.test
index ad0fa0a7ce4e3..02bb0c9afdfcd 100644
--- a/compiler-rt/test/fuzzer/exit_on_src_pos.test
+++ b/compiler-rt/test/fuzzer/exit_on_src_pos.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows until symbolization works properly.
+UNSUPPORTED: windows
 # Temporary use -mllvm -use-unknown-locations=Disable so that
 # all instructions have debug info (file line numbers) attached.
 # TODO: Find out why test fails on Darwin with -O2.
diff --git a/compiler-rt/test/fuzzer/fuzzer-customcrossover.test b/compiler-rt/test/fuzzer/fuzzer-customcrossover.test
index 0835081f289a1..ce84f133cb40e 100644
--- a/compiler-rt/test/fuzzer/fuzzer-customcrossover.test
+++ b/compiler-rt/test/fuzzer/fuzzer-customcrossover.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows since LLVMFuzzerCustomCrossOver does not yet work.
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/CustomCrossOverTest.cpp -o %t-CustomCrossOverTest
 
 RUN: not %run %t-CustomCrossOverTest -seed=1 -runs=1000000                2>&1 | FileCheck %s --check-prefix=CHECK_CO
diff --git a/compiler-rt/test/fuzzer/fuzzer-custommutator.test b/compiler-rt/test/fuzzer/fuzzer-custommutator.test
index 51aef2373cca0..5c47ff9ce5de7 100644
--- a/compiler-rt/test/fuzzer/fuzzer-custommutator.test
+++ b/compiler-rt/test/fuzzer/fuzzer-custommutator.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows since LLVMFuzzerCustomMutator does not yet work.
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/CustomMutatorTest.cpp -o %t-CustomMutatorTest
 RUN: not %run %t-CustomMutatorTest 2>&1 | FileCheck %s --check-prefix=LLVMFuzzerCustomMutator
 LLVMFuzzerCustomMutator: In LLVMFuzzerCustomMutator
diff --git a/compiler-rt/test/fuzzer/fuzzer-flags.test b/compiler-rt/test/fuzzer/fuzzer-flags.test
index 916c6eed889f0..340e0b07cee61 100644
--- a/compiler-rt/test/fuzzer/fuzzer-flags.test
+++ b/compiler-rt/test/fuzzer/fuzzer-flags.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows since LLVMFuzzerInitialize does not yet work.
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/FlagsTest.cpp -o %t-FlagsTest
 RUN: %run %t-FlagsTest -runs=10 -foo_bar=1 2>&1 | FileCheck %s --check-prefix=FOO_BAR
 FOO_BAR: WARNING: unrecognized flag '-foo_bar=1'; use -help=1 to list all flags
diff --git a/compiler-rt/test/fuzzer/fuzzer-oom.test b/compiler-rt/test/fuzzer/fuzzer-oom.test
index e82fb47c5bed4..e21d471ec5783 100644
--- a/compiler-rt/test/fuzzer/fuzzer-oom.test
+++ b/compiler-rt/test/fuzzer/fuzzer-oom.test
@@ -1,4 +1,5 @@
-UNSUPPORTED: aarch64
+# FIXME: Disabled on Windows until symbolization works properly.
+UNSUPPORTED: aarch64, windows
 RUN: %cpp_compiler %S/OutOfMemoryTest.cpp -o %t-OutOfMemoryTest
 RUN: %cpp_compiler %S/OutOfMemorySingleLargeMallocTest.cpp -o %t-OutOfMemorySingleLargeMallocTest
 RUN: %cpp_compiler %S/AccumulateAllocationsTest.cpp -o %t-AccumulateAllocationsTest
diff --git a/compiler-rt/test/fuzzer/handle-unstable.test b/compiler-rt/test/fuzzer/handle-unstable.test
index a0b7c8303914d..ea8d9e8d8fd65 100644
--- a/compiler-rt/test/fuzzer/handle-unstable.test
+++ b/compiler-rt/test/fuzzer/handle-unstable.test
@@ -1,5 +1,6 @@
 # Tests -handle_unstable
-UNSUPPORTED: aarch64
+# FIXME: Disabled on Windows until symbolization works properly.
+UNSUPPORTED: aarch64, windows
 
 RUN: %cpp_compiler %S/PrintUnstableStatsTest.cpp -o %t-HandleUnstableTest
 
diff --git a/compiler-rt/test/fuzzer/initialize.test b/compiler-rt/test/fuzzer/initialize.test
index dc6e8697558e5..0ff3796dc9095 100644
--- a/compiler-rt/test/fuzzer/initialize.test
+++ b/compiler-rt/test/fuzzer/initialize.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows because memmem is a GNU extension.
+UNSUPPORTED: windows
 CHECK: BINGO
 RUN: %cpp_compiler %S/InitializeTest.cpp -o %t-InitializeTest
 RUN: not %run %t-InitializeTest -use_value_profile=1 2>&1 | FileCheck %s
diff --git a/compiler-rt/test/fuzzer/lit.cfg b/compiler-rt/test/fuzzer/lit.cfg
index 8a44860d4a5dc..81e73c21244ed 100644
--- a/compiler-rt/test/fuzzer/lit.cfg
+++ b/compiler-rt/test/fuzzer/lit.cfg
@@ -24,15 +24,17 @@ else:
 # the test runner updated.
 config.test_format = lit.formats.ShTest(execute_external)
 
-# LeakSanitizer is not supported on OSX right now.
-if sys.platform.startswith('darwin') or sys.platform.startswith('freebsd'):
+# LeakSanitizer is not supported on OSX or Windows right now.
+if (sys.platform.startswith('darwin') or
+    sys.platform.startswith('freebsd') or
+    sys.platform.startswith('win')):
   lit_config.note('lsan feature unavailable')
 else:
   lit_config.note('lsan feature available')
   config.available_features.add('lsan')
 
-# MemorySanitizer is not supported on OSX right now
-if sys.platform.startswith('darwin'):
+# MemorySanitizer is not supported on OSX or Windows right now
+if sys.platform.startswith('darwin') or sys.platform.startswith('win'):
   lit_config.note('msan feature unavailable')
   assert 'msan' not in config.available_features
 else:
@@ -70,7 +72,11 @@ def generate_compiler_cmd(is_cpp=True, fuzzer_enabled=True, msan_enabled=False):
   else:
     link_cmd = '-lstdc++'
 
-  std_cmd = '--driver-mode=g++ -std=c++11' if is_cpp else ''
+  if is_cpp and not sys.platform.startswith('win'):
+    std_cmd = '--driver-mode=g++ -std=c++11'
+  else:
+    std_cmd = ''
+
   if msan_enabled:
     sanitizers = ['memory']
   else:
diff --git a/compiler-rt/test/fuzzer/merge-control-file.test b/compiler-rt/test/fuzzer/merge-control-file.test
index 64b747116a9ff..60b2a6a627ca4 100644
--- a/compiler-rt/test/fuzzer/merge-control-file.test
+++ b/compiler-rt/test/fuzzer/merge-control-file.test
@@ -1,6 +1,8 @@
 XFAIL: ios
 RUN: mkdir -p %t
-RUN: %cpp_compiler %S/FullCoverageSetTest.cpp -o %t/T
+# Use a ".exe" extension because it is needed on Windows to call system()
+# to execute itself again.
+RUN: %cpp_compiler %S/FullCoverageSetTest.cpp -o %t/T.exe
 
 RUN: rm -rf %t/T0 %t/T1 %t/T2
 RUN: mkdir -p %t/T0 %t/T1 %t/T2
@@ -11,9 +13,9 @@ RUN: echo ..Z... > %t/T0/3
 # Test what happens if the control file is junk.
 
 RUN: echo JUNK > %t/MCF
-RUN: not %run %t/T -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=JUNK
+RUN: not %run %t/T.exe -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=JUNK
 RUN: echo 3 > %t/MCF; echo 0 >> %t/MCF; echo %t/T1/1 >> %t/MCF
-RUN: not %run %t/T -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=JUNK
+RUN: not %run %t/T.exe -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=JUNK
 JUNK: MERGE-OUTER: non-empty control file provided: {{.*}}MCF
 JUNK: MERGE-OUTER: bad control file, will overwrite it
 
@@ -22,18 +24,18 @@ JUNK: MERGE-OUTER: bad control file, will overwrite it
 
 RUN: rm -f %t/T1/*; cp %t/T0/* %t/T1
 RUN: echo 3 > %t/MCF; echo 0 >> %t/MCF; echo %t/T1/1 >> %t/MCF; echo %t/T1/2 >> %t/MCF; echo %t/T1/3 >> %t/MCF
-RUN: %run %t/T -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=OK_0
+RUN: %run %t/T.exe -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=OK_0
 OK_0: MERGE-OUTER: control file ok, 3 files total, first not processed file 0
 OK_0: MERGE-OUTER: 3 new files with {{.*}} new features added
 
 RUN: rm -f %t/T1/*; cp %t/T0/* %t/T1
 RUN: echo 3 > %t/MCF; echo 0 >> %t/MCF; echo %t/T1/1 >> %t/MCF; echo %t/T1/2 >> %t/MCF; echo %t/T1/3 >> %t/MCF
-RUN: %run %t/T -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF -save_coverage_summary=%t/SUMMARY 2>&1 | FileCheck %s --check-prefix=SAVE_SUMMARY
+RUN: %run %t/T.exe -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF -save_coverage_summary=%t/SUMMARY 2>&1 | FileCheck %s --check-prefix=SAVE_SUMMARY
 SAVE_SUMMARY: MERGE-OUTER: writing coverage summary for 3 files to {{.*}}/SUMMARY
 
 RUN: rm -f %t/T1/*; cp %t/T0/* %t/T1
 RUN: echo 3 > %t/MCF; echo 0 >> %t/MCF; echo %t/T1/1 >> %t/MCF; echo %t/T1/2 >> %t/MCF; echo %t/T1/3 >> %t/MCF
-RUN: %run %t/T -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF -load_coverage_summary=%t/SUMMARY 2>&1 | FileCheck %s --check-prefix=LOAD_SUMMARY
+RUN: %run %t/T.exe -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF -load_coverage_summary=%t/SUMMARY 2>&1 | FileCheck %s --check-prefix=LOAD_SUMMARY
 LOAD_SUMMARY: MERGE-OUTER: coverage summary loaded from
 
 RUN: rm -f %t/T1/*; cp %t/T0/* %t/T1
@@ -42,7 +44,7 @@ RUN: echo STARTED 0 1 >> %t/MCF
 RUN: echo DONE 0 11 >> %t/MCF
 RUN: echo STARTED 1 2 >> %t/MCF
 RUN: echo DONE 1 12 >> %t/MCF
-RUN: %run %t/T -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=OK_2
+RUN: %run %t/T.exe -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=OK_2
 OK_2: MERGE-OUTER: control file ok, 3 files total, first not processed file 2
 OK_2: MERGE-OUTER: 3 new files with {{.*}} new features added
 
@@ -54,5 +56,5 @@ RUN: echo STARTED 1 2 >> %t/MCF
 RUN: echo DONE 1 12 >> %t/MCF
 RUN: echo STARTED 2 2 >> %t/MCF
 RUN: echo DONE 2 13 >> %t/MCF
-RUN: %run %t/T -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=OK_3
+RUN: %run %t/T.exe -merge=1 %t/T1 %t/T2 -merge_control_file=%t/MCF 2>&1 | FileCheck %s --check-prefix=OK_3
 OK_3: MERGE-OUTER: nothing to do, merge has been completed before
diff --git a/compiler-rt/test/fuzzer/merge-posix.test b/compiler-rt/test/fuzzer/merge-posix.test
index db0a48b5481e4..883b7b6be97b5 100644
--- a/compiler-rt/test/fuzzer/merge-posix.test
+++ b/compiler-rt/test/fuzzer/merge-posix.test
@@ -1,4 +1,5 @@
 XFAIL: ios
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/FullCoverageSetTest.cpp -o %t-FullCoverageSetTest
 
 RUN: rm -rf  %tmp/T1 %tmp/T2
diff --git a/compiler-rt/test/fuzzer/merge-sigusr.test b/compiler-rt/test/fuzzer/merge-sigusr.test
index a03e5440a8b88..44448ca29e638 100644
--- a/compiler-rt/test/fuzzer/merge-sigusr.test
+++ b/compiler-rt/test/fuzzer/merge-sigusr.test
@@ -1,5 +1,7 @@
 # Check that libFuzzer honors SIGUSR1/SIGUSR2
-UNSUPPORTED: darwin
+# FIXME: Disabled on Windows for now because of reliance on posix only features
+# (eg: export, "&", pkill).
+UNSUPPORTED: darwin, windows
 RUN: rm -rf %t
 RUN: mkdir -p %t
 RUN: %cpp_compiler %S/SleepOneSecondTest.cpp -o %t/LFSIGUSR
diff --git a/compiler-rt/test/fuzzer/print_unstable_stats.test b/compiler-rt/test/fuzzer/print_unstable_stats.test
index c20efe9408ce0..41b2791307650 100644
--- a/compiler-rt/test/fuzzer/print_unstable_stats.test
+++ b/compiler-rt/test/fuzzer/print_unstable_stats.test
@@ -1,10 +1,11 @@
 # Tests -print_unstable_stats
-UNSUPPORTED: aarch64
+# Disabled on Windows because of differences symbolizing and flakiness.
+UNSUPPORTED: aarch64, windows
 
 RUN: %cpp_compiler %S/PrintUnstableStatsTest.cpp -o %t-PrintUnstableStatsTest
 
 RUN: %run %t-PrintUnstableStatsTest -print_unstable_stats=1 -runs=100000 2>&1 | FileCheck %s --check-prefix=LONG
-; We do not observe ini functions since we take the minimum hit counts, and minimum hit counts for ini is 0.
+# We do not observe ini functions since we take the minimum hit counts, and minimum hit counts for ini is 0.
 LONG: UNSTABLE_FUNCTIONS:
 LONG-NOT: det0()
 LONG-NOT: det1()
diff --git a/compiler-rt/test/fuzzer/sigusr.test b/compiler-rt/test/fuzzer/sigusr.test
index 0b3ddc72832de..fa477a76eea1e 100644
--- a/compiler-rt/test/fuzzer/sigusr.test
+++ b/compiler-rt/test/fuzzer/sigusr.test
@@ -1,4 +1,6 @@
-UNSUPPORTED: darwin
+# FIXME: Disabled on Windows for now because of reliance on posix only features
+# (eg: export, "&", pkill).
+UNSUPPORTED: darwin, windows
 # Check that libFuzzer honors SIGUSR1/SIGUSR2
 RUN: rm -rf %t
 RUN: mkdir -p %t
diff --git a/compiler-rt/test/fuzzer/standalone.test b/compiler-rt/test/fuzzer/standalone.test
index cd2422e4e6838..da7cf1eb7ef67 100644
--- a/compiler-rt/test/fuzzer/standalone.test
+++ b/compiler-rt/test/fuzzer/standalone.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows because memmem is a GNU extension.
+UNSUPPORTED: windows
 RUN: %no_fuzzer_c_compiler %libfuzzer_src/standalone/StandaloneFuzzTargetMain.c -c -o %t_1.o
 RUN: %no_fuzzer_cpp_compiler %S/InitializeTest.cpp -c -o %t_2.o
 
diff --git a/compiler-rt/test/fuzzer/symbolize-deadlock.test b/compiler-rt/test/fuzzer/symbolize-deadlock.test
index 25b519fd3fed0..9a1084f649d78 100644
--- a/compiler-rt/test/fuzzer/symbolize-deadlock.test
+++ b/compiler-rt/test/fuzzer/symbolize-deadlock.test
@@ -1,2 +1,4 @@
+# Disabled on Widows because <unistd.h> is a posix-only header.
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/SymbolizeDeadlock.cpp -o %t
 RUN: not %run %t -rss_limit_mb=20 2>&1
diff --git a/compiler-rt/test/fuzzer/trace-malloc-threaded.test b/compiler-rt/test/fuzzer/trace-malloc-threaded.test
index 8f972d61f5c63..f38005c1d2f65 100644
--- a/compiler-rt/test/fuzzer/trace-malloc-threaded.test
+++ b/compiler-rt/test/fuzzer/trace-malloc-threaded.test
@@ -1,6 +1,7 @@
 // FIXME: This test infinite loops on darwin because it crashes
 // printing a stack trace repeatedly
-UNSUPPORTED: darwin, aarch64
+// FIXME: Disabled on Windows because of a crash (possibly related to above).
+UNSUPPORTED: darwin, aarch64, windows
 
 RUN: %cpp_compiler %S/TraceMallocThreadedTest.cpp -o \
 RUN:   %t-TraceMallocThreadedTest
diff --git a/compiler-rt/test/fuzzer/trace-malloc-unbalanced.test b/compiler-rt/test/fuzzer/trace-malloc-unbalanced.test
index 193df01ddeff0..6ba26bb30ec31 100644
--- a/compiler-rt/test/fuzzer/trace-malloc-unbalanced.test
+++ b/compiler-rt/test/fuzzer/trace-malloc-unbalanced.test
@@ -1,6 +1,7 @@
 // FIXME: This test infinite loops on darwin because it crashes
 // printing a stack trace repeatedly
-UNSUPPORTED: darwin
+// FIXME: Disabled on Windows because of reliance on shebang line and failure.
+UNSUPPORTED: darwin, windows
 
 // Verifies lib/fuzzer/scripts/unbalanced_allocs.py script
 
diff --git a/compiler-rt/test/fuzzer/ulimit.test b/compiler-rt/test/fuzzer/ulimit.test
index 076866c509401..7cf4c0a68866b 100644
--- a/compiler-rt/test/fuzzer/ulimit.test
+++ b/compiler-rt/test/fuzzer/ulimit.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows for now because Windows has no ulimit command.
+UNSUPPORTED: windows
 RUN: %cpp_compiler %S/SimpleTest.cpp -o %t-SimpleTest
 RUN: ulimit -s 1000
 RUN: not %run %t-SimpleTest
diff --git a/compiler-rt/test/fuzzer/value-profile-cmp.test b/compiler-rt/test/fuzzer/value-profile-cmp.test
index b927422d10ff5..8d964b10b34eb 100644
--- a/compiler-rt/test/fuzzer/value-profile-cmp.test
+++ b/compiler-rt/test/fuzzer/value-profile-cmp.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows because of hangs.
+UNSUPPORTED: windows
 CHECK: BINGO
 RUN: %cpp_compiler %S/SimpleCmpTest.cpp -o %t-SimpleCmpTest
 RUN: not %run %t-SimpleCmpTest -seed=1 -use_cmp=0 -use_value_profile=1 -runs=100000000 2>&1 | FileCheck %s
diff --git a/compiler-rt/test/fuzzer/value-profile-cmp4.test b/compiler-rt/test/fuzzer/value-profile-cmp4.test
index 05bc3f435912d..e5ac29f81c43f 100644
--- a/compiler-rt/test/fuzzer/value-profile-cmp4.test
+++ b/compiler-rt/test/fuzzer/value-profile-cmp4.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows because of hangs.
+UNSUPPORTED: windows
 CHECK: BINGO
 RUN: %cpp_compiler %S/AbsNegAndConstant64Test.cpp -o %t-AbsNegAndConstant64Test
 RUN: not %run %t-AbsNegAndConstant64Test -seed=1 -use_cmp=0 -use_value_profile=1 -runs=100000000 2>&1 | FileCheck %s
diff --git a/compiler-rt/test/fuzzer/value-profile-load.test b/compiler-rt/test/fuzzer/value-profile-load.test
index 607b81cd527fe..b6baf13200d4a 100644
--- a/compiler-rt/test/fuzzer/value-profile-load.test
+++ b/compiler-rt/test/fuzzer/value-profile-load.test
@@ -1,3 +1,5 @@
+# FIXME: Disabled on Windows because of hangs.
+UNSUPPORTED: windows
 CHECK: AddressSanitizer: global-buffer-overflow
 RUN: %cpp_compiler %S/LoadTest.cpp -fsanitize-coverage=trace-gep -o %t-LoadTest
 RUN: not %run %t-LoadTest -seed=2 -use_cmp=0 -use_value_profile=1 -runs=20000000 2>&1 | FileCheck %s