diff --git a/flang/test/Semantics/OpenMP/allocate-clause01.f90 b/flang/test/Semantics/OpenMP/allocate-clause01.f90
index e059a4a61a90f..ec6f2836b2c9f 100644
--- a/flang/test/Semantics/OpenMP/allocate-clause01.f90
+++ b/flang/test/Semantics/OpenMP/allocate-clause01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate-directive.f90 b/flang/test/Semantics/OpenMP/allocate-directive.f90
index 1db13df419382..abd063d170885 100644
--- a/flang/test/Semantics/OpenMP/allocate-directive.f90
+++ b/flang/test/Semantics/OpenMP/allocate-directive.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate01.f90 b/flang/test/Semantics/OpenMP/allocate01.f90
index a91076c80b1f9..595cecbdeca4a 100644
--- a/flang/test/Semantics/OpenMP/allocate01.f90
+++ b/flang/test/Semantics/OpenMP/allocate01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate02.f90 b/flang/test/Semantics/OpenMP/allocate02.f90
index dc4194aca7f12..e81faa39593b7 100644
--- a/flang/test/Semantics/OpenMP/allocate02.f90
+++ b/flang/test/Semantics/OpenMP/allocate02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate03.f90 b/flang/test/Semantics/OpenMP/allocate03.f90
index 30a015f26c312..747977047b307 100644
--- a/flang/test/Semantics/OpenMP/allocate03.f90
+++ b/flang/test/Semantics/OpenMP/allocate03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate04.f90 b/flang/test/Semantics/OpenMP/allocate04.f90
index b8a8709411615..e583499e8b8c0 100644
--- a/flang/test/Semantics/OpenMP/allocate04.f90
+++ b/flang/test/Semantics/OpenMP/allocate04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate05.f90 b/flang/test/Semantics/OpenMP/allocate05.f90
index 92eeaf4222ac9..58f3a110ff0bf 100644
--- a/flang/test/Semantics/OpenMP/allocate05.f90
+++ b/flang/test/Semantics/OpenMP/allocate05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate06.f90 b/flang/test/Semantics/OpenMP/allocate06.f90
index c4474560bea39..34b75b8130bed 100644
--- a/flang/test/Semantics/OpenMP/allocate06.f90
+++ b/flang/test/Semantics/OpenMP/allocate06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate07.f90 b/flang/test/Semantics/OpenMP/allocate07.f90
index 3211c0bf28b9d..eb520ebf5335a 100644
--- a/flang/test/Semantics/OpenMP/allocate07.f90
+++ b/flang/test/Semantics/OpenMP/allocate07.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate08.f90 b/flang/test/Semantics/OpenMP/allocate08.f90
index 152ad07544ea4..cd59243c0d193 100644
--- a/flang/test/Semantics/OpenMP/allocate08.f90
+++ b/flang/test/Semantics/OpenMP/allocate08.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocate09.f90 b/flang/test/Semantics/OpenMP/allocate09.f90
index 639d23cd6d30f..958084dfaafc2 100644
--- a/flang/test/Semantics/OpenMP/allocate09.f90
+++ b/flang/test/Semantics/OpenMP/allocate09.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocators01.f90 b/flang/test/Semantics/OpenMP/allocators01.f90
index 02d686b49716e..ccc7e35a7a9b3 100644
--- a/flang/test/Semantics/OpenMP/allocators01.f90
+++ b/flang/test/Semantics/OpenMP/allocators01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocators02.f90 b/flang/test/Semantics/OpenMP/allocators02.f90
index 9d8644bc30c61..876d492f16931 100644
--- a/flang/test/Semantics/OpenMP/allocators02.f90
+++ b/flang/test/Semantics/OpenMP/allocators02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocators03.f90 b/flang/test/Semantics/OpenMP/allocators03.f90
index 85ab91fde5e01..2cef712d62ba5 100644
--- a/flang/test/Semantics/OpenMP/allocators03.f90
+++ b/flang/test/Semantics/OpenMP/allocators03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocators04.f90 b/flang/test/Semantics/OpenMP/allocators04.f90
index 0c6e994e137ad..863bafd189101 100644
--- a/flang/test/Semantics/OpenMP/allocators04.f90
+++ b/flang/test/Semantics/OpenMP/allocators04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocators05.f90 b/flang/test/Semantics/OpenMP/allocators05.f90
index 07f1357b75b55..871e44bc716aa 100644
--- a/flang/test/Semantics/OpenMP/allocators05.f90
+++ b/flang/test/Semantics/OpenMP/allocators05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/allocators06.f90 b/flang/test/Semantics/OpenMP/allocators06.f90
index d3773c05a485d..4e6f072a3c185 100644
--- a/flang/test/Semantics/OpenMP/allocators06.f90
+++ b/flang/test/Semantics/OpenMP/allocators06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/atomic-hint-clause.f90 b/flang/test/Semantics/OpenMP/atomic-hint-clause.f90
index 3cbde3ab586ca..3c6752178f2be 100644
--- a/flang/test/Semantics/OpenMP/atomic-hint-clause.f90
+++ b/flang/test/Semantics/OpenMP/atomic-hint-clause.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp 
diff --git a/flang/test/Semantics/OpenMP/atomic.f90 b/flang/test/Semantics/OpenMP/atomic.f90
index 44f06b7460bf1..2f270ce333381 100644
--- a/flang/test/Semantics/OpenMP/atomic.f90
+++ b/flang/test/Semantics/OpenMP/atomic.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 use omp_lib
 ! Check OpenMP 2.13.6 atomic Construct
diff --git a/flang/test/Semantics/OpenMP/atomic01.f90 b/flang/test/Semantics/OpenMP/atomic01.f90
index 868c7623928ae..c418b1d391cbf 100644
--- a/flang/test/Semantics/OpenMP/atomic01.f90
+++ b/flang/test/Semantics/OpenMP/atomic01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/atomic02.f90 b/flang/test/Semantics/OpenMP/atomic02.f90
index db67fa63dcdf5..4fc25651ca9f0 100644
--- a/flang/test/Semantics/OpenMP/atomic02.f90
+++ b/flang/test/Semantics/OpenMP/atomic02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/atomic03.f90 b/flang/test/Semantics/OpenMP/atomic03.f90
index 9bcbace10fb60..b91783ae7a9f9 100644
--- a/flang/test/Semantics/OpenMP/atomic03.f90
+++ b/flang/test/Semantics/OpenMP/atomic03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/atomic04.f90 b/flang/test/Semantics/OpenMP/atomic04.f90
index c0419a69d2dd7..c5e5cdd29c1ab 100644
--- a/flang/test/Semantics/OpenMP/atomic04.f90
+++ b/flang/test/Semantics/OpenMP/atomic04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/atomic05.f90 b/flang/test/Semantics/OpenMP/atomic05.f90
index 7b970dba8e49f..826ea75ba401d 100644
--- a/flang/test/Semantics/OpenMP/atomic05.f90
+++ b/flang/test/Semantics/OpenMP/atomic05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
diff --git a/flang/test/Semantics/OpenMP/barrier.f90 b/flang/test/Semantics/OpenMP/barrier.f90
index 1483fbd08f958..5fc3f7f3bd70b 100644
--- a/flang/test/Semantics/OpenMP/barrier.f90
+++ b/flang/test/Semantics/OpenMP/barrier.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 !$omp barrier
diff --git a/flang/test/Semantics/OpenMP/clause-validity01.f90 b/flang/test/Semantics/OpenMP/clause-validity01.f90
index 21b99cb82549a..d6d27970d496a 100644
--- a/flang/test/Semantics/OpenMP/clause-validity01.f90
+++ b/flang/test/Semantics/OpenMP/clause-validity01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/combined-constructs.f90 b/flang/test/Semantics/OpenMP/combined-constructs.f90
index 35ab6fcac58b9..ba504d1b8e22e 100644
--- a/flang/test/Semantics/OpenMP/combined-constructs.f90
+++ b/flang/test/Semantics/OpenMP/combined-constructs.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 program main
diff --git a/flang/test/Semantics/OpenMP/common-block.f90 b/flang/test/Semantics/OpenMP/common-block.f90
index e1ddd120da857..4ddc5474a628b 100644
--- a/flang/test/Semantics/OpenMP/common-block.f90
+++ b/flang/test/Semantics/OpenMP/common-block.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-symbols %s | FileCheck %s
 
 program main
diff --git a/flang/test/Semantics/OpenMP/compiler-directive.f90 b/flang/test/Semantics/OpenMP/compiler-directive.f90
index 5d3e9bae27fd8..07363ac5ac1e4 100644
--- a/flang/test/Semantics/OpenMP/compiler-directive.f90
+++ b/flang/test/Semantics/OpenMP/compiler-directive.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! CompilerDirective with openmp tests
 
diff --git a/flang/test/Semantics/OpenMP/copyin01.f90 b/flang/test/Semantics/OpenMP/copyin01.f90
index 0051b5d441f05..387a9fc7cf0b5 100644
--- a/flang/test/Semantics/OpenMP/copyin01.f90
+++ b/flang/test/Semantics/OpenMP/copyin01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.1 copyin Clause
diff --git a/flang/test/Semantics/OpenMP/copyin02.f90 b/flang/test/Semantics/OpenMP/copyin02.f90
index 09b876677ea31..92512890e3ede 100644
--- a/flang/test/Semantics/OpenMP/copyin02.f90
+++ b/flang/test/Semantics/OpenMP/copyin02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.1 copyin Clause
diff --git a/flang/test/Semantics/OpenMP/copyin03.f90 b/flang/test/Semantics/OpenMP/copyin03.f90
index 7c3759aa2e116..5c0a2e873d818 100644
--- a/flang/test/Semantics/OpenMP/copyin03.f90
+++ b/flang/test/Semantics/OpenMP/copyin03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.1 copyin Clause
diff --git a/flang/test/Semantics/OpenMP/copyin04.f90 b/flang/test/Semantics/OpenMP/copyin04.f90
index 6f5e8dfef217b..7cbee5f4afab0 100644
--- a/flang/test/Semantics/OpenMP/copyin04.f90
+++ b/flang/test/Semantics/OpenMP/copyin04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.1 copyin Clause
diff --git a/flang/test/Semantics/OpenMP/copyin05.f90 b/flang/test/Semantics/OpenMP/copyin05.f90
index 142d5a7345c6e..aec6a7f880705 100644
--- a/flang/test/Semantics/OpenMP/copyin05.f90
+++ b/flang/test/Semantics/OpenMP/copyin05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.1 copyin Clause
diff --git a/flang/test/Semantics/OpenMP/copying.f90 b/flang/test/Semantics/OpenMP/copying.f90
index 63fb39a0f26e5..d56d2b8932cf0 100644
--- a/flang/test/Semantics/OpenMP/copying.f90
+++ b/flang/test/Semantics/OpenMP/copying.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp -Werror -pedantic
 ! OpenMP Version 5.0
 ! 2.19.4.4 firstprivate Clause
diff --git a/flang/test/Semantics/OpenMP/copyprivate01.f90 b/flang/test/Semantics/OpenMP/copyprivate01.f90
index d5cf273476078..4920d7abbe7c5 100644
--- a/flang/test/Semantics/OpenMP/copyprivate01.f90
+++ b/flang/test/Semantics/OpenMP/copyprivate01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.2 copyprivate Clause
diff --git a/flang/test/Semantics/OpenMP/copyprivate02.f90 b/flang/test/Semantics/OpenMP/copyprivate02.f90
index 35fd6dddd20c9..2157cd4cb558c 100644
--- a/flang/test/Semantics/OpenMP/copyprivate02.f90
+++ b/flang/test/Semantics/OpenMP/copyprivate02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.2 copyprivate Clause
diff --git a/flang/test/Semantics/OpenMP/copyprivate03.f90 b/flang/test/Semantics/OpenMP/copyprivate03.f90
index 9d39fdb6b13c8..f1433ced8aac1 100644
--- a/flang/test/Semantics/OpenMP/copyprivate03.f90
+++ b/flang/test/Semantics/OpenMP/copyprivate03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.4.2 copyprivate Clause
diff --git a/flang/test/Semantics/OpenMP/critical-empty.f90 b/flang/test/Semantics/OpenMP/critical-empty.f90
index 2001c8a14a7ba..706f6d806f557 100644
--- a/flang/test/Semantics/OpenMP/critical-empty.f90
+++ b/flang/test/Semantics/OpenMP/critical-empty.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp 
 ! Test that there are no errors for an empty critical construct
 
diff --git a/flang/test/Semantics/OpenMP/critical-hint-clause.f90 b/flang/test/Semantics/OpenMP/critical-hint-clause.f90
index f35eea149135a..9b2126ee254f9 100644
--- a/flang/test/Semantics/OpenMP/critical-hint-clause.f90
+++ b/flang/test/Semantics/OpenMP/critical-hint-clause.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp 
diff --git a/flang/test/Semantics/OpenMP/dealloc.f90 b/flang/test/Semantics/OpenMP/dealloc.f90
index b25fa62377f68..876f74f96bcc7 100644
--- a/flang/test/Semantics/OpenMP/dealloc.f90
+++ b/flang/test/Semantics/OpenMP/dealloc.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 
 ! Test to check that no errors are present when allocate statements
diff --git a/flang/test/Semantics/OpenMP/declarative-directive.f90 b/flang/test/Semantics/OpenMP/declarative-directive.f90
index 4d10dc2d1b123..15a41479fdfd3 100644
--- a/flang/test/Semantics/OpenMP/declarative-directive.f90
+++ b/flang/test/Semantics/OpenMP/declarative-directive.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! Check OpenMP declarative directives
diff --git a/flang/test/Semantics/OpenMP/declare-target-common-block.f90 b/flang/test/Semantics/OpenMP/declare-target-common-block.f90
index 33a093a03a227..9e123add228f5 100644
--- a/flang/test/Semantics/OpenMP/declare-target-common-block.f90
+++ b/flang/test/Semantics/OpenMP/declare-target-common-block.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-symbols %s | FileCheck %s
 
 PROGRAM main
diff --git a/flang/test/Semantics/OpenMP/declare-target01.f90 b/flang/test/Semantics/OpenMP/declare-target01.f90
index 549f708b08f91..a21d431c1b4fa 100644
--- a/flang/test/Semantics/OpenMP/declare-target01.f90
+++ b/flang/test/Semantics/OpenMP/declare-target01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/declare-target02.f90 b/flang/test/Semantics/OpenMP/declare-target02.f90
index 8166e10d702b8..af9e766dddb15 100644
--- a/flang/test/Semantics/OpenMP/declare-target02.f90
+++ b/flang/test/Semantics/OpenMP/declare-target02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/declare-target03.f90 b/flang/test/Semantics/OpenMP/declare-target03.f90
index bb1ed90e390f3..14694b62149a9 100644
--- a/flang/test/Semantics/OpenMP/declare-target03.f90
+++ b/flang/test/Semantics/OpenMP/declare-target03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp -pedantic
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/declare-target04.f90 b/flang/test/Semantics/OpenMP/declare-target04.f90
index 24f8b4abecd13..90b681e359755 100644
--- a/flang/test/Semantics/OpenMP/declare-target04.f90
+++ b/flang/test/Semantics/OpenMP/declare-target04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/declare-target05.f90 b/flang/test/Semantics/OpenMP/declare-target05.f90
index 2334a8506b7e4..7154f760f0ad7 100644
--- a/flang/test/Semantics/OpenMP/declare-target05.f90
+++ b/flang/test/Semantics/OpenMP/declare-target05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/declare-target06.f90 b/flang/test/Semantics/OpenMP/declare-target06.f90
index a1c55d39e1b68..ffd7f038445e6 100644
--- a/flang/test/Semantics/OpenMP/declare-target06.f90
+++ b/flang/test/Semantics/OpenMP/declare-target06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/declare-target07.f90 b/flang/test/Semantics/OpenMP/declare-target07.f90
index 22b4a4bd081d7..d901c9ccadff3 100644
--- a/flang/test/Semantics/OpenMP/declare-target07.f90
+++ b/flang/test/Semantics/OpenMP/declare-target07.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 
 module my_module
diff --git a/flang/test/Semantics/OpenMP/default-clause.f90 b/flang/test/Semantics/OpenMP/default-clause.f90
index 9cde77be2babe..eaea88115f48e 100644
--- a/flang/test/Semantics/OpenMP/default-clause.f90
+++ b/flang/test/Semantics/OpenMP/default-clause.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-symbols %s | FileCheck %s
 
 ! Test symbols generated in block constructs in the 
diff --git a/flang/test/Semantics/OpenMP/default-none.f90 b/flang/test/Semantics/OpenMP/default-none.f90
index 11ba878ea7794..44ddc96712995 100644
--- a/flang/test/Semantics/OpenMP/default-none.f90
+++ b/flang/test/Semantics/OpenMP/default-none.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! Positive tests for default(none)
 subroutine sb2(x)
diff --git a/flang/test/Semantics/OpenMP/default.f90 b/flang/test/Semantics/OpenMP/default.f90
index 94de7fa468692..917eeaa0f4acb 100644
--- a/flang/test/Semantics/OpenMP/default.f90
+++ b/flang/test/Semantics/OpenMP/default.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.1 default Clause
diff --git a/flang/test/Semantics/OpenMP/default02.f90 b/flang/test/Semantics/OpenMP/default02.f90
index 23f994bcc3920..08200a4124280 100644
--- a/flang/test/Semantics/OpenMP/default02.f90
+++ b/flang/test/Semantics/OpenMP/default02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.1 default Clause - a positive test case.
diff --git a/flang/test/Semantics/OpenMP/depend01.f90 b/flang/test/Semantics/OpenMP/depend01.f90
index 29468f4358855..870e3865a4050 100644
--- a/flang/test/Semantics/OpenMP/depend01.f90
+++ b/flang/test/Semantics/OpenMP/depend01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.13.9 Depend Clause
diff --git a/flang/test/Semantics/OpenMP/depend02.f90 b/flang/test/Semantics/OpenMP/depend02.f90
index 76c02c8f9cbab..a3191e7ed12c1 100644
--- a/flang/test/Semantics/OpenMP/depend02.f90
+++ b/flang/test/Semantics/OpenMP/depend02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.13.9 Depend Clause
diff --git a/flang/test/Semantics/OpenMP/depend03.f90 b/flang/test/Semantics/OpenMP/depend03.f90
index e0eb683d252ef..e7b88acd954f8 100644
--- a/flang/test/Semantics/OpenMP/depend03.f90
+++ b/flang/test/Semantics/OpenMP/depend03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.13.9 Depend Clause
diff --git a/flang/test/Semantics/OpenMP/device-clause01.f90 b/flang/test/Semantics/OpenMP/device-clause01.f90
index 6f95d162790d5..88bc29e43bf63 100644
--- a/flang/test/Semantics/OpenMP/device-clause01.f90
+++ b/flang/test/Semantics/OpenMP/device-clause01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.2
 ! 13.2 Device clause
diff --git a/flang/test/Semantics/OpenMP/device-constructs.f90 b/flang/test/Semantics/OpenMP/device-constructs.f90
index 1ac00ef922c6b..6018f8fa9dfb0 100644
--- a/flang/test/Semantics/OpenMP/device-constructs.f90
+++ b/flang/test/Semantics/OpenMP/device-constructs.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! Check OpenMP clause validity for the following directives:
 !     2.10 Device constructs
diff --git a/flang/test/Semantics/OpenMP/do-collapse-positivecases.f90 b/flang/test/Semantics/OpenMP/do-collapse-positivecases.f90
index 6ad14fa01bca0..2065b4eacdfd0 100644
--- a/flang/test/Semantics/OpenMP/do-collapse-positivecases.f90
+++ b/flang/test/Semantics/OpenMP/do-collapse-positivecases.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Collapse Clause Positive cases
diff --git a/flang/test/Semantics/OpenMP/do-collapse.f90 b/flang/test/Semantics/OpenMP/do-collapse.f90
index 145b7b75d28df..c8bbb39519f52 100644
--- a/flang/test/Semantics/OpenMP/do-collapse.f90
+++ b/flang/test/Semantics/OpenMP/do-collapse.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Collapse Clause
diff --git a/flang/test/Semantics/OpenMP/do-cycle.f90 b/flang/test/Semantics/OpenMP/do-cycle.f90
index b6617acb0794a..bdfd93b46e43e 100644
--- a/flang/test/Semantics/OpenMP/do-cycle.f90
+++ b/flang/test/Semantics/OpenMP/do-cycle.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! Check for cycle statements leaving an OpenMP structured block
diff --git a/flang/test/Semantics/OpenMP/do-ordered-positivecases.f90 b/flang/test/Semantics/OpenMP/do-ordered-positivecases.f90
index d4c4e5b1bf2f4..02d91a85cbf29 100644
--- a/flang/test/Semantics/OpenMP/do-ordered-positivecases.f90
+++ b/flang/test/Semantics/OpenMP/do-ordered-positivecases.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Ordered Clause positive cases.
diff --git a/flang/test/Semantics/OpenMP/do-ordered.f90 b/flang/test/Semantics/OpenMP/do-ordered.f90
index 79ded3e1b6fe6..7bc4a92c68eb4 100644
--- a/flang/test/Semantics/OpenMP/do-ordered.f90
+++ b/flang/test/Semantics/OpenMP/do-ordered.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Ordered Clause
diff --git a/flang/test/Semantics/OpenMP/do-schedule01.f90 b/flang/test/Semantics/OpenMP/do-schedule01.f90
index 1e0a8a613135c..3fc46ff77206c 100644
--- a/flang/test/Semantics/OpenMP/do-schedule01.f90
+++ b/flang/test/Semantics/OpenMP/do-schedule01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Schedule Clause
diff --git a/flang/test/Semantics/OpenMP/do-schedule02.f90 b/flang/test/Semantics/OpenMP/do-schedule02.f90
index a7cbdc24e83a2..d08c69645ebbf 100644
--- a/flang/test/Semantics/OpenMP/do-schedule02.f90
+++ b/flang/test/Semantics/OpenMP/do-schedule02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Schedule Clause
diff --git a/flang/test/Semantics/OpenMP/do-schedule03.f90 b/flang/test/Semantics/OpenMP/do-schedule03.f90
index 8787b094d581a..f7167e14b3f55 100644
--- a/flang/test/Semantics/OpenMP/do-schedule03.f90
+++ b/flang/test/Semantics/OpenMP/do-schedule03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Schedule Clause
diff --git a/flang/test/Semantics/OpenMP/do-schedule04.f90 b/flang/test/Semantics/OpenMP/do-schedule04.f90
index 0d1e189593eac..fb816aab256d8 100644
--- a/flang/test/Semantics/OpenMP/do-schedule04.f90
+++ b/flang/test/Semantics/OpenMP/do-schedule04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Schedule Clause
diff --git a/flang/test/Semantics/OpenMP/do01-positivecase.f90 b/flang/test/Semantics/OpenMP/do01-positivecase.f90
index 905fdbaf18476..c2b0894d7071e 100644
--- a/flang/test/Semantics/OpenMP/do01-positivecase.f90
+++ b/flang/test/Semantics/OpenMP/do01-positivecase.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do01.f90 b/flang/test/Semantics/OpenMP/do01.f90
index 78c3ba38bc873..0cef5b710c09f 100644
--- a/flang/test/Semantics/OpenMP/do01.f90
+++ b/flang/test/Semantics/OpenMP/do01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do02.f90 b/flang/test/Semantics/OpenMP/do02.f90
deleted file mode 100644
index 9749991e4f96b..0000000000000
--- a/flang/test/Semantics/OpenMP/do02.f90
+++ /dev/null
@@ -1,21 +0,0 @@
-! RUN: %S/test_errors.sh %s %t %flang -fopenmp
-! XFAIL: *
-
-! OpenMP Version 4.5
-! 2.7.1 Loop Construct
-! Exit statement terminating !$OMP DO loop
-
-program omp_do
-  integer i, j, k
-
-  !$omp do
-  do i = 1, 10
-    do j = 1, 10
-      print *, "Hello"
-    end do
-    !ERROR: EXIT statement terminating !$OMP DO loop
-    exit
-  end do
-  !$omp end do
-
-end program omp_do
diff --git a/flang/test/Semantics/OpenMP/do03.f90 b/flang/test/Semantics/OpenMP/do03.f90
index 7ec84a0a34245..62733f89d528b 100644
--- a/flang/test/Semantics/OpenMP/do03.f90
+++ b/flang/test/Semantics/OpenMP/do03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/do04-positivecase.f90 b/flang/test/Semantics/OpenMP/do04-positivecase.f90
index eb2d67bb8ceb2..7de3908096ad0 100644
--- a/flang/test/Semantics/OpenMP/do04-positivecase.f90
+++ b/flang/test/Semantics/OpenMP/do04-positivecase.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Do Loop Constructs
diff --git a/flang/test/Semantics/OpenMP/do04.f90 b/flang/test/Semantics/OpenMP/do04.f90
index 6690f4927f6a9..7e214ecc5a5c0 100644
--- a/flang/test/Semantics/OpenMP/do04.f90
+++ b/flang/test/Semantics/OpenMP/do04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do05-positivecase.f90 b/flang/test/Semantics/OpenMP/do05-positivecase.f90
index 4e02235f58a1a..9daea23551eae 100644
--- a/flang/test/Semantics/OpenMP/do05-positivecase.f90
+++ b/flang/test/Semantics/OpenMP/do05-positivecase.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct restrictions on single directive.
diff --git a/flang/test/Semantics/OpenMP/do05.f90 b/flang/test/Semantics/OpenMP/do05.f90
index c0f240db57b65..73c656690715f 100644
--- a/flang/test/Semantics/OpenMP/do05.f90
+++ b/flang/test/Semantics/OpenMP/do05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct restrictions on single directive.
diff --git a/flang/test/Semantics/OpenMP/do06-positivecases.f90 b/flang/test/Semantics/OpenMP/do06-positivecases.f90
index 2713b55fa2ecb..b66a7ef4ccc3f 100644
--- a/flang/test/Semantics/OpenMP/do06-positivecases.f90
+++ b/flang/test/Semantics/OpenMP/do06-positivecases.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do06.f90 b/flang/test/Semantics/OpenMP/do06.f90
index 86790c2930e24..9efb50b7ca28e 100644
--- a/flang/test/Semantics/OpenMP/do06.f90
+++ b/flang/test/Semantics/OpenMP/do06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do07.f90 b/flang/test/Semantics/OpenMP/do07.f90
index 44fe5f86045ac..2b371d7a939ac 100644
--- a/flang/test/Semantics/OpenMP/do07.f90
+++ b/flang/test/Semantics/OpenMP/do07.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: not %flang -fsyntax-only -fopenmp %s 2>&1 | FileCheck %s
 ! REQUIRES: shell
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/do08.f90 b/flang/test/Semantics/OpenMP/do08.f90
index 5143dff0dd315..5282b230ed72f 100644
--- a/flang/test/Semantics/OpenMP/do08.f90
+++ b/flang/test/Semantics/OpenMP/do08.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do09.f90 b/flang/test/Semantics/OpenMP/do09.f90
index af9f2e294ace9..e87d94cc20a15 100644
--- a/flang/test/Semantics/OpenMP/do09.f90
+++ b/flang/test/Semantics/OpenMP/do09.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do10.f90 b/flang/test/Semantics/OpenMP/do10.f90
index 7e8105e125a92..07c7161e6ab1e 100644
--- a/flang/test/Semantics/OpenMP/do10.f90
+++ b/flang/test/Semantics/OpenMP/do10.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do11.f90 b/flang/test/Semantics/OpenMP/do11.f90
index faab457efff3c..86b4e919e7205 100644
--- a/flang/test/Semantics/OpenMP/do11.f90
+++ b/flang/test/Semantics/OpenMP/do11.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Do Loop Constructs
diff --git a/flang/test/Semantics/OpenMP/do12.f90 b/flang/test/Semantics/OpenMP/do12.f90
index a057a246f7a99..e49304e868982 100644
--- a/flang/test/Semantics/OpenMP/do12.f90
+++ b/flang/test/Semantics/OpenMP/do12.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Do Loop constructs.
diff --git a/flang/test/Semantics/OpenMP/do13.f90 b/flang/test/Semantics/OpenMP/do13.f90
index 6e9d1dddade4c..9c9cdf42fe26f 100644
--- a/flang/test/Semantics/OpenMP/do13.f90
+++ b/flang/test/Semantics/OpenMP/do13.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do14.f90 b/flang/test/Semantics/OpenMP/do14.f90
index 5e8a5a64c2979..33fed997a47fb 100644
--- a/flang/test/Semantics/OpenMP/do14.f90
+++ b/flang/test/Semantics/OpenMP/do14.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Do Loop constructs.
diff --git a/flang/test/Semantics/OpenMP/do15.f90 b/flang/test/Semantics/OpenMP/do15.f90
index 45c591e66361c..890a8dc7e416e 100644
--- a/flang/test/Semantics/OpenMP/do15.f90
+++ b/flang/test/Semantics/OpenMP/do15.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do16.f90 b/flang/test/Semantics/OpenMP/do16.f90
index 15d13f683cf12..94cc69db71301 100644
--- a/flang/test/Semantics/OpenMP/do16.f90
+++ b/flang/test/Semantics/OpenMP/do16.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/do17.f90 b/flang/test/Semantics/OpenMP/do17.f90
index c0c59f16dee1b..a12a3dfb4d139 100644
--- a/flang/test/Semantics/OpenMP/do17.f90
+++ b/flang/test/Semantics/OpenMP/do17.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.1 Do Loop constructs.
diff --git a/flang/test/Semantics/OpenMP/do18.f90 b/flang/test/Semantics/OpenMP/do18.f90
index cdac323240eeb..32ed756691af1 100644
--- a/flang/test/Semantics/OpenMP/do18.f90
+++ b/flang/test/Semantics/OpenMP/do18.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fdebug-unparse-with-symbols %s 2>&1 | FileCheck %s
 ! RUN: %flang_fc1 -fopenmp -fdebug-unparse-with-symbols %s 2>&1 | FileCheck %s
 ! CHECK-NOT: do *[1-9]
diff --git a/flang/test/Semantics/OpenMP/do19.f90 b/flang/test/Semantics/OpenMP/do19.f90
index 3dab59d615e5e..e5bb6da7d08bc 100644
--- a/flang/test/Semantics/OpenMP/do19.f90
+++ b/flang/test/Semantics/OpenMP/do19.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-unparse-with-symbols %s 2>&1 | FileCheck %s
 ! CHECK-NOT: do *[1-9]
 ! CHECK: omp simd
diff --git a/flang/test/Semantics/OpenMP/do20.f90 b/flang/test/Semantics/OpenMP/do20.f90
index 915d01e69edd7..cabe07e0419ce 100644
--- a/flang/test/Semantics/OpenMP/do20.f90
+++ b/flang/test/Semantics/OpenMP/do20.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! OpenMP 5.2 5.1.1
diff --git a/flang/test/Semantics/OpenMP/firstprivate01.f90 b/flang/test/Semantics/OpenMP/firstprivate01.f90
index 0c576a9f07a42..28521dab78c60 100644
--- a/flang/test/Semantics/OpenMP/firstprivate01.f90
+++ b/flang/test/Semantics/OpenMP/firstprivate01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.4 firstprivate Clause
diff --git a/flang/test/Semantics/OpenMP/firstprivate02.f90 b/flang/test/Semantics/OpenMP/firstprivate02.f90
index eb2597cb1cc40..a27508a9a57c8 100644
--- a/flang/test/Semantics/OpenMP/firstprivate02.f90
+++ b/flang/test/Semantics/OpenMP/firstprivate02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.2, Sections 3.2.1 & 5.3
 subroutine omp_firstprivate(init)
diff --git a/flang/test/Semantics/OpenMP/flush01.f90 b/flang/test/Semantics/OpenMP/flush01.f90
index 27324de4a8f7a..0b5ce50e24eb4 100644
--- a/flang/test/Semantics/OpenMP/flush01.f90
+++ b/flang/test/Semantics/OpenMP/flush01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! 2.17.8 Flush construct [OpenMP 5.0]
diff --git a/flang/test/Semantics/OpenMP/flush02.f90 b/flang/test/Semantics/OpenMP/flush02.f90
index dbb57ac81450e..f7569cdc574a9 100644
--- a/flang/test/Semantics/OpenMP/flush02.f90
+++ b/flang/test/Semantics/OpenMP/flush02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/if-clause.f90 b/flang/test/Semantics/OpenMP/if-clause.f90
index 493c6c873bfbf..4a2e28e54f06e 100644
--- a/flang/test/Semantics/OpenMP/if-clause.f90
+++ b/flang/test/Semantics/OpenMP/if-clause.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! Check OpenMP 'if' clause validity for all directives that can have it
 
diff --git a/flang/test/Semantics/OpenMP/implicit-dsa.f90 b/flang/test/Semantics/OpenMP/implicit-dsa.f90
index 92d2421d06f97..590e0f2701946 100644
--- a/flang/test/Semantics/OpenMP/implicit-dsa.f90
+++ b/flang/test/Semantics/OpenMP/implicit-dsa.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! Test symbols generated in block constructs that have implicitly
diff --git a/flang/test/Semantics/OpenMP/invalid-branch.f90 b/flang/test/Semantics/OpenMP/invalid-branch.f90
index ed9e4d268f65a..3f2eacec22bca 100644
--- a/flang/test/Semantics/OpenMP/invalid-branch.f90
+++ b/flang/test/Semantics/OpenMP/invalid-branch.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: not %flang -fsyntax-only -fopenmp %s 2>&1 | FileCheck %s
 ! REQUIRES: shell
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/lastprivate01.f90 b/flang/test/Semantics/OpenMP/lastprivate01.f90
index 4fae4829d8862..af207948f23a3 100644
--- a/flang/test/Semantics/OpenMP/lastprivate01.f90
+++ b/flang/test/Semantics/OpenMP/lastprivate01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.5 lastprivate Clause
diff --git a/flang/test/Semantics/OpenMP/lastprivate02.f90 b/flang/test/Semantics/OpenMP/lastprivate02.f90
index c5bf9d7f50d04..632b0a49250aa 100644
--- a/flang/test/Semantics/OpenMP/lastprivate02.f90
+++ b/flang/test/Semantics/OpenMP/lastprivate02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.5 lastprivate Clause
diff --git a/flang/test/Semantics/OpenMP/lastprivate03.f90 b/flang/test/Semantics/OpenMP/lastprivate03.f90
index d7fe0c162f27c..512dd7dc72470 100644
--- a/flang/test/Semantics/OpenMP/lastprivate03.f90
+++ b/flang/test/Semantics/OpenMP/lastprivate03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.2, Sections 3.2.1 & 5.3
 subroutine omp_lastprivate(init)
diff --git a/flang/test/Semantics/OpenMP/linear-iter.f90 b/flang/test/Semantics/OpenMP/linear-iter.f90
index 8102c1a03cd37..9bd3f570965a3 100644
--- a/flang/test/Semantics/OpenMP/linear-iter.f90
+++ b/flang/test/Semantics/OpenMP/linear-iter.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! Various checks with the ordered construct
diff --git a/flang/test/Semantics/OpenMP/loop-association.f90 b/flang/test/Semantics/OpenMP/loop-association.f90
index d2167663c5dde..99eab75b0173d 100644
--- a/flang/test/Semantics/OpenMP/loop-association.f90
+++ b/flang/test/Semantics/OpenMP/loop-association.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! Check the association between OpenMPLoopConstruct and DoConstruct
diff --git a/flang/test/Semantics/OpenMP/loop-simd01.f90 b/flang/test/Semantics/OpenMP/loop-simd01.f90
index 18878645c0c6f..0315c79ea530d 100644
--- a/flang/test/Semantics/OpenMP/loop-simd01.f90
+++ b/flang/test/Semantics/OpenMP/loop-simd01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/map-clause.f90 b/flang/test/Semantics/OpenMP/map-clause.f90
index a7430c3edeb94..8d1e45aa55cf0 100644
--- a/flang/test/Semantics/OpenMP/map-clause.f90
+++ b/flang/test/Semantics/OpenMP/map-clause.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! Check OpenMP MAP clause validity. Section 5.8.3 OpenMP 5.2.
 
diff --git a/flang/test/Semantics/OpenMP/modfile-threadprivate.f90 b/flang/test/Semantics/OpenMP/modfile-threadprivate.f90
index 74147c0494a54..febcd58ccb360 100644
--- a/flang/test/Semantics/OpenMP/modfile-threadprivate.f90
+++ b/flang/test/Semantics/OpenMP/modfile-threadprivate.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_modfile.py %s %flang_fc1 -fopenmp
 ! Check correct modfile generation for OpenMP threadprivate directive.
 
diff --git a/flang/test/Semantics/OpenMP/nested-barrier.f90 b/flang/test/Semantics/OpenMP/nested-barrier.f90
index cad31d7985607..14877dbcdfa1c 100644
--- a/flang/test/Semantics/OpenMP/nested-barrier.f90
+++ b/flang/test/Semantics/OpenMP/nested-barrier.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! Various checks with the nesting of BARRIER construct
diff --git a/flang/test/Semantics/OpenMP/nested-cancel.f90 b/flang/test/Semantics/OpenMP/nested-cancel.f90
index afd94a591a067..6dc566d87b099 100644
--- a/flang/test/Semantics/OpenMP/nested-cancel.f90
+++ b/flang/test/Semantics/OpenMP/nested-cancel.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 5.0
diff --git a/flang/test/Semantics/OpenMP/nested-cancellation-point.f90 b/flang/test/Semantics/OpenMP/nested-cancellation-point.f90
index 5392a31b23312..d9bbb3200664e 100644
--- a/flang/test/Semantics/OpenMP/nested-cancellation-point.f90
+++ b/flang/test/Semantics/OpenMP/nested-cancellation-point.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 5.0
diff --git a/flang/test/Semantics/OpenMP/nested-distribute.f90 b/flang/test/Semantics/OpenMP/nested-distribute.f90
index 5103790392897..df3e0b0d85935 100644
--- a/flang/test/Semantics/OpenMP/nested-distribute.f90
+++ b/flang/test/Semantics/OpenMP/nested-distribute.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! Check OpenMP clause validity for the following directives:
 !     2.10 Device constructs
diff --git a/flang/test/Semantics/OpenMP/nested-master.f90 b/flang/test/Semantics/OpenMP/nested-master.f90
index ef7d2cef6f88a..da6b3db8defbf 100644
--- a/flang/test/Semantics/OpenMP/nested-master.f90
+++ b/flang/test/Semantics/OpenMP/nested-master.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! Various checks with the nesting of MASTER construct
diff --git a/flang/test/Semantics/OpenMP/nested-simd.f90 b/flang/test/Semantics/OpenMP/nested-simd.f90
index 4149b6d97e9dc..14e298f3843df 100644
--- a/flang/test/Semantics/OpenMP/nested-simd.f90
+++ b/flang/test/Semantics/OpenMP/nested-simd.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! Various checks with the nesting of SIMD construct
diff --git a/flang/test/Semantics/OpenMP/nested-target.f90 b/flang/test/Semantics/OpenMP/nested-target.f90
index 2267f70715d3e..3d015c6a0a5b0 100644
--- a/flang/test/Semantics/OpenMP/nested-target.f90
+++ b/flang/test/Semantics/OpenMP/nested-target.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp -Werror -pedantic
 
 ! OpenMP Version 5.0
diff --git a/flang/test/Semantics/OpenMP/nested-teams.f90 b/flang/test/Semantics/OpenMP/nested-teams.f90
index 80c59e07fbaa6..df2b092aaaaec 100644
--- a/flang/test/Semantics/OpenMP/nested-teams.f90
+++ b/flang/test/Semantics/OpenMP/nested-teams.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 5.0
diff --git a/flang/test/Semantics/OpenMP/nested01.f90 b/flang/test/Semantics/OpenMP/nested01.f90
index 49c964ab86aa6..df53ecdba4f5d 100644
--- a/flang/test/Semantics/OpenMP/nested01.f90
+++ b/flang/test/Semantics/OpenMP/nested01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! Check OpenMP 2.17 Nesting of Regions
diff --git a/flang/test/Semantics/OpenMP/no-dowhile-in-parallel.f90 b/flang/test/Semantics/OpenMP/no-dowhile-in-parallel.f90
index fb864fd32ef00..9e5d703b380af 100644
--- a/flang/test/Semantics/OpenMP/no-dowhile-in-parallel.f90
+++ b/flang/test/Semantics/OpenMP/no-dowhile-in-parallel.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 subroutine bug48308(x,i)
diff --git a/flang/test/Semantics/OpenMP/nontemporal.f90 b/flang/test/Semantics/OpenMP/nontemporal.f90
index 6d24849575ee9..866996aeb3536 100644
--- a/flang/test/Semantics/OpenMP/nontemporal.f90
+++ b/flang/test/Semantics/OpenMP/nontemporal.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s  %flang -fopenmp
 ! REQUIRES: shell
 ! Check OpenMP clause validity for NONTEMPORAL clause
diff --git a/flang/test/Semantics/OpenMP/omp-atomic-assignment-stmt.f90 b/flang/test/Semantics/OpenMP/omp-atomic-assignment-stmt.f90
index d9ced2cd79501..8d3470591f745 100644
--- a/flang/test/Semantics/OpenMP/omp-atomic-assignment-stmt.f90
+++ b/flang/test/Semantics/OpenMP/omp-atomic-assignment-stmt.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/omp-do-collapse1.f90 b/flang/test/Semantics/OpenMP/omp-do-collapse1.f90
index 81f87d8239e53..d3550d52f294d 100644
--- a/flang/test/Semantics/OpenMP/omp-do-collapse1.f90
+++ b/flang/test/Semantics/OpenMP/omp-do-collapse1.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: not %flang_fc1 -fdebug-unparse-with-symbols -fopenmp %s 2>&1 | FileCheck %s
 ! OpenMP Version 4.5
 ! 2.7.1 Loop Construct
diff --git a/flang/test/Semantics/OpenMP/order-clause01.f90 b/flang/test/Semantics/OpenMP/order-clause01.f90
index 247791fac15b4..8359aefc324de 100644
--- a/flang/test/Semantics/OpenMP/order-clause01.f90
+++ b/flang/test/Semantics/OpenMP/order-clause01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 
 subroutine omp_order()
diff --git a/flang/test/Semantics/OpenMP/ordered-simd.f90 b/flang/test/Semantics/OpenMP/ordered-simd.f90
index c33ec745f2dda..3dd2c7232bcac 100644
--- a/flang/test/Semantics/OpenMP/ordered-simd.f90
+++ b/flang/test/Semantics/OpenMP/ordered-simd.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! Various checks with the ordered construct
diff --git a/flang/test/Semantics/OpenMP/ordered01.f90 b/flang/test/Semantics/OpenMP/ordered01.f90
index 9433120fab10f..69d61f134740d 100644
--- a/flang/test/Semantics/OpenMP/ordered01.f90
+++ b/flang/test/Semantics/OpenMP/ordered01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/ordered02.f90 b/flang/test/Semantics/OpenMP/ordered02.f90
index ed320c82a9794..0ecc7ea141a36 100644
--- a/flang/test/Semantics/OpenMP/ordered02.f90
+++ b/flang/test/Semantics/OpenMP/ordered02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/ordered03.f90 b/flang/test/Semantics/OpenMP/ordered03.f90
index 8dd4d035212d8..59e312f8cfc2a 100644
--- a/flang/test/Semantics/OpenMP/ordered03.f90
+++ b/flang/test/Semantics/OpenMP/ordered03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/parallel-critical-do.f90 b/flang/test/Semantics/OpenMP/parallel-critical-do.f90
index 6e10b46dea9a0..6a40f0872e8b4 100644
--- a/flang/test/Semantics/OpenMP/parallel-critical-do.f90
+++ b/flang/test/Semantics/OpenMP/parallel-critical-do.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! Check that loop iteration variables are private and predetermined, even when
diff --git a/flang/test/Semantics/OpenMP/parallel-private01.f90 b/flang/test/Semantics/OpenMP/parallel-private01.f90
index a3d332c95ed25..a460059732a57 100644
--- a/flang/test/Semantics/OpenMP/parallel-private01.f90
+++ b/flang/test/Semantics/OpenMP/parallel-private01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.3 parallel private Clause
diff --git a/flang/test/Semantics/OpenMP/parallel-private02.f90 b/flang/test/Semantics/OpenMP/parallel-private02.f90
index 8cb72159d6ab5..89e9ff1af5dbb 100644
--- a/flang/test/Semantics/OpenMP/parallel-private02.f90
+++ b/flang/test/Semantics/OpenMP/parallel-private02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.3 parallel private Clause
diff --git a/flang/test/Semantics/OpenMP/parallel-private03.f90 b/flang/test/Semantics/OpenMP/parallel-private03.f90
index 24a096302e53d..c832645042e03 100644
--- a/flang/test/Semantics/OpenMP/parallel-private03.f90
+++ b/flang/test/Semantics/OpenMP/parallel-private03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.3 parallel private Clause
diff --git a/flang/test/Semantics/OpenMP/parallel-private04.f90 b/flang/test/Semantics/OpenMP/parallel-private04.f90
index 67a669c9882a5..52a4f659d6536 100644
--- a/flang/test/Semantics/OpenMP/parallel-private04.f90
+++ b/flang/test/Semantics/OpenMP/parallel-private04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.3 parallel private Clause
diff --git a/flang/test/Semantics/OpenMP/parallel-sections-do.f90 b/flang/test/Semantics/OpenMP/parallel-sections-do.f90
index 39102175299ba..b8ca1096d06b0 100644
--- a/flang/test/Semantics/OpenMP/parallel-sections-do.f90
+++ b/flang/test/Semantics/OpenMP/parallel-sections-do.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! Check that loop iteration variables are private and predetermined, even when
diff --git a/flang/test/Semantics/OpenMP/parallel-sections01.f90 b/flang/test/Semantics/OpenMP/parallel-sections01.f90
index b073cc8223b61..e9790b3155687 100644
--- a/flang/test/Semantics/OpenMP/parallel-sections01.f90
+++ b/flang/test/Semantics/OpenMP/parallel-sections01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
diff --git a/flang/test/Semantics/OpenMP/parallel-shared01.f90 b/flang/test/Semantics/OpenMP/parallel-shared01.f90
index 7abfe1f7b1637..89584d6cc123a 100644
--- a/flang/test/Semantics/OpenMP/parallel-shared01.f90
+++ b/flang/test/Semantics/OpenMP/parallel-shared01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.2 parallel shared Clause
diff --git a/flang/test/Semantics/OpenMP/parallel-shared02.f90 b/flang/test/Semantics/OpenMP/parallel-shared02.f90
index f59f5236dfd93..d7c4d4b0fea16 100644
--- a/flang/test/Semantics/OpenMP/parallel-shared02.f90
+++ b/flang/test/Semantics/OpenMP/parallel-shared02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.2 parallel shared Clause
diff --git a/flang/test/Semantics/OpenMP/parallel-shared03.f90 b/flang/test/Semantics/OpenMP/parallel-shared03.f90
index 3d9111c7aaf10..5283918756ac8 100644
--- a/flang/test/Semantics/OpenMP/parallel-shared03.f90
+++ b/flang/test/Semantics/OpenMP/parallel-shared03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.2 parallel shared Clause
diff --git a/flang/test/Semantics/OpenMP/parallel-shared04.f90 b/flang/test/Semantics/OpenMP/parallel-shared04.f90
index 06b7fcfa01d7a..c1e998ee8b06f 100644
--- a/flang/test/Semantics/OpenMP/parallel-shared04.f90
+++ b/flang/test/Semantics/OpenMP/parallel-shared04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 !RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.2 parallel shared Clause
diff --git a/flang/test/Semantics/OpenMP/parallel01.f90 b/flang/test/Semantics/OpenMP/parallel01.f90
index 6d5dd581a9f23..3e7a678844bd2 100644
--- a/flang/test/Semantics/OpenMP/parallel01.f90
+++ b/flang/test/Semantics/OpenMP/parallel01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: not %flang -fsyntax-only -fopenmp %s 2>&1 | FileCheck %s
 ! OpenMP Version 4.5
 ! 2.5 parallel construct.
diff --git a/flang/test/Semantics/OpenMP/parallel02.f90 b/flang/test/Semantics/OpenMP/parallel02.f90
index eff0e7c70d1a0..3587afaeb122b 100644
--- a/flang/test/Semantics/OpenMP/parallel02.f90
+++ b/flang/test/Semantics/OpenMP/parallel02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: not %flang -fsyntax-only -fopenmp %s 2>&1 | FileCheck %s
 ! OpenMP Version 4.5
 ! 2.5 parallel construct.
diff --git a/flang/test/Semantics/OpenMP/private-is-pointer-allocatable-check.f90 b/flang/test/Semantics/OpenMP/private-is-pointer-allocatable-check.f90
index 7b3915d9a1104..d6631b4f625af 100644
--- a/flang/test/Semantics/OpenMP/private-is-pointer-allocatable-check.f90
+++ b/flang/test/Semantics/OpenMP/private-is-pointer-allocatable-check.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fsyntax-only %s
 
 subroutine s
diff --git a/flang/test/Semantics/OpenMP/private01.f90 b/flang/test/Semantics/OpenMP/private01.f90
index 052823a9f78a6..3597e20705975 100644
--- a/flang/test/Semantics/OpenMP/private01.f90
+++ b/flang/test/Semantics/OpenMP/private01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.3 private Clause
diff --git a/flang/test/Semantics/OpenMP/private02.f90 b/flang/test/Semantics/OpenMP/private02.f90
index a81e31998eebb..a7bcb79e9872e 100644
--- a/flang/test/Semantics/OpenMP/private02.f90
+++ b/flang/test/Semantics/OpenMP/private02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.3 private Clause
diff --git a/flang/test/Semantics/OpenMP/reduction-subtract.f90 b/flang/test/Semantics/OpenMP/reduction-subtract.f90
index d4034743a14dc..2601c767c5970 100644
--- a/flang/test/Semantics/OpenMP/reduction-subtract.f90
+++ b/flang/test/Semantics/OpenMP/reduction-subtract.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.2
 ! Minus operation is deprecated in reduction
diff --git a/flang/test/Semantics/OpenMP/reduction01.f90 b/flang/test/Semantics/OpenMP/reduction01.f90
index 0e1a8a571c584..e33f7ece8e927 100644
--- a/flang/test/Semantics/OpenMP/reduction01.f90
+++ b/flang/test/Semantics/OpenMP/reduction01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction02.f90 b/flang/test/Semantics/OpenMP/reduction02.f90
index 4fd9fbe2d8a53..792a88f773b26 100644
--- a/flang/test/Semantics/OpenMP/reduction02.f90
+++ b/flang/test/Semantics/OpenMP/reduction02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction03.f90 b/flang/test/Semantics/OpenMP/reduction03.f90
index 1ddc2903fecc4..a24349668db06 100644
--- a/flang/test/Semantics/OpenMP/reduction03.f90
+++ b/flang/test/Semantics/OpenMP/reduction03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction04.f90 b/flang/test/Semantics/OpenMP/reduction04.f90
index 319ed9f245abe..5c434e33a04ef 100644
--- a/flang/test/Semantics/OpenMP/reduction04.f90
+++ b/flang/test/Semantics/OpenMP/reduction04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction05.f90 b/flang/test/Semantics/OpenMP/reduction05.f90
index aa115ed7454ba..f859f9f1fd463 100644
--- a/flang/test/Semantics/OpenMP/reduction05.f90
+++ b/flang/test/Semantics/OpenMP/reduction05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction06.f90 b/flang/test/Semantics/OpenMP/reduction06.f90
index 58290c61cae86..5bcdce852a5d0 100644
--- a/flang/test/Semantics/OpenMP/reduction06.f90
+++ b/flang/test/Semantics/OpenMP/reduction06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction07.f90 b/flang/test/Semantics/OpenMP/reduction07.f90
index 98ed69a8d846d..bf252fde72b34 100644
--- a/flang/test/Semantics/OpenMP/reduction07.f90
+++ b/flang/test/Semantics/OpenMP/reduction07.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction08.f90 b/flang/test/Semantics/OpenMP/reduction08.f90
index 99163327cdafa..b26fc533869cd 100644
--- a/flang/test/Semantics/OpenMP/reduction08.f90
+++ b/flang/test/Semantics/OpenMP/reduction08.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause Positive cases
diff --git a/flang/test/Semantics/OpenMP/reduction09.f90 b/flang/test/Semantics/OpenMP/reduction09.f90
index 095b49ba0c400..c5d95349020ff 100644
--- a/flang/test/Semantics/OpenMP/reduction09.f90
+++ b/flang/test/Semantics/OpenMP/reduction09.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause Positive cases.
diff --git a/flang/test/Semantics/OpenMP/reduction10.f90 b/flang/test/Semantics/OpenMP/reduction10.f90
index 0f94594408b88..394ee737d72f8 100644
--- a/flang/test/Semantics/OpenMP/reduction10.f90
+++ b/flang/test/Semantics/OpenMP/reduction10.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.15.3.6 Reduction Clause
diff --git a/flang/test/Semantics/OpenMP/reduction11.f90 b/flang/test/Semantics/OpenMP/reduction11.f90
index 3893fe70b407f..95a356f87526a 100644
--- a/flang/test/Semantics/OpenMP/reduction11.f90
+++ b/flang/test/Semantics/OpenMP/reduction11.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-symbols -o - %s 2>&1 | FileCheck %s
 ! Check intrinsic reduction symbols (in this case "max" are marked as INTRINSIC
 
diff --git a/flang/test/Semantics/OpenMP/reduction12.f90 b/flang/test/Semantics/OpenMP/reduction12.f90
index f896ca4aa60b6..bfd6e04fc485a 100644
--- a/flang/test/Semantics/OpenMP/reduction12.f90
+++ b/flang/test/Semantics/OpenMP/reduction12.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 
 ! OpenMP 5.2: Section 5.5.5 : A procedure pointer must not appear in a
diff --git a/flang/test/Semantics/OpenMP/requires-atomic01.f90 b/flang/test/Semantics/OpenMP/requires-atomic01.f90
index b39c9cdcc0bb3..a14491653eb3f 100644
--- a/flang/test/Semantics/OpenMP/requires-atomic01.f90
+++ b/flang/test/Semantics/OpenMP/requires-atomic01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-parse-tree %s 2>&1 | FileCheck %s
 ! Ensure that requires atomic_default_mem_order is used to update atomic
 ! operations with no explicit memory order set.
diff --git a/flang/test/Semantics/OpenMP/requires-atomic02.f90 b/flang/test/Semantics/OpenMP/requires-atomic02.f90
index 3af83970e7927..5175e8faaf8d7 100644
--- a/flang/test/Semantics/OpenMP/requires-atomic02.f90
+++ b/flang/test/Semantics/OpenMP/requires-atomic02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-parse-tree %s 2>&1 | FileCheck %s
 ! Ensure that requires atomic_default_mem_order is used to update atomic
 ! operations with no explicit memory order set. ACQ_REL clause tested here.
diff --git a/flang/test/Semantics/OpenMP/requires01.f90 b/flang/test/Semantics/OpenMP/requires01.f90
index 007135749cc82..35989889af4ec 100644
--- a/flang/test/Semantics/OpenMP/requires01.f90
+++ b/flang/test/Semantics/OpenMP/requires01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 !$omp requires reverse_offload unified_shared_memory
diff --git a/flang/test/Semantics/OpenMP/requires02.f90 b/flang/test/Semantics/OpenMP/requires02.f90
index 974bcceb10c6f..7d689fb273029 100644
--- a/flang/test/Semantics/OpenMP/requires02.f90
+++ b/flang/test/Semantics/OpenMP/requires02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/requires03.f90 b/flang/test/Semantics/OpenMP/requires03.f90
index 4a23a6a4105fe..c8b09018c8358 100644
--- a/flang/test/Semantics/OpenMP/requires03.f90
+++ b/flang/test/Semantics/OpenMP/requires03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/requires04.f90 b/flang/test/Semantics/OpenMP/requires04.f90
index bb4101c1cbd6c..fd6da68b428d6 100644
--- a/flang/test/Semantics/OpenMP/requires04.f90
+++ b/flang/test/Semantics/OpenMP/requires04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/requires05.f90 b/flang/test/Semantics/OpenMP/requires05.f90
index dd27e3895e394..0b566807a2836 100644
--- a/flang/test/Semantics/OpenMP/requires05.f90
+++ b/flang/test/Semantics/OpenMP/requires05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/requires06.f90 b/flang/test/Semantics/OpenMP/requires06.f90
index ba9bbf31b6e07..551dd9d103823 100644
--- a/flang/test/Semantics/OpenMP/requires06.f90
+++ b/flang/test/Semantics/OpenMP/requires06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/requires07.f90 b/flang/test/Semantics/OpenMP/requires07.f90
index 2a36b4def9199..d6926c5fdb38f 100644
--- a/flang/test/Semantics/OpenMP/requires07.f90
+++ b/flang/test/Semantics/OpenMP/requires07.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/requires08.f90 b/flang/test/Semantics/OpenMP/requires08.f90
index 5f3b084078ccf..0ad7f53eaf512 100644
--- a/flang/test/Semantics/OpenMP/requires08.f90
+++ b/flang/test/Semantics/OpenMP/requires08.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/requires09.f90 b/flang/test/Semantics/OpenMP/requires09.f90
index 2fa5d950b9c2d..d4d5d6168ae7e 100644
--- a/flang/test/Semantics/OpenMP/requires09.f90
+++ b/flang/test/Semantics/OpenMP/requires09.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.4 Requires directive
diff --git a/flang/test/Semantics/OpenMP/resolve01.f90 b/flang/test/Semantics/OpenMP/resolve01.f90
index 79b67885b8b9c..0af616178116d 100644
--- a/flang/test/Semantics/OpenMP/resolve01.f90
+++ b/flang/test/Semantics/OpenMP/resolve01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! 2.4 An array section designates a subset of the elements in an array. Although
diff --git a/flang/test/Semantics/OpenMP/resolve02.f90 b/flang/test/Semantics/OpenMP/resolve02.f90
index 7c3d6331c82ae..cc54f623fa376 100644
--- a/flang/test/Semantics/OpenMP/resolve02.f90
+++ b/flang/test/Semantics/OpenMP/resolve02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! Test the effect to name resolution from illegal clause
diff --git a/flang/test/Semantics/OpenMP/resolve03.f90 b/flang/test/Semantics/OpenMP/resolve03.f90
index ebc66ca12ebf4..62bd4e4f919d2 100644
--- a/flang/test/Semantics/OpenMP/resolve03.f90
+++ b/flang/test/Semantics/OpenMP/resolve03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! 2.15.3 Although variables in common blocks can be accessed by use association
diff --git a/flang/test/Semantics/OpenMP/resolve04.f90 b/flang/test/Semantics/OpenMP/resolve04.f90
index 7c61950c57f66..6efceed8302ea 100644
--- a/flang/test/Semantics/OpenMP/resolve04.f90
+++ b/flang/test/Semantics/OpenMP/resolve04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! 2.15.3 Data-Sharing Attribute Clauses
diff --git a/flang/test/Semantics/OpenMP/resolve05.f90 b/flang/test/Semantics/OpenMP/resolve05.f90
index c4cebb48ac5c2..5ec4b58f4b8ff 100644
--- a/flang/test/Semantics/OpenMP/resolve05.f90
+++ b/flang/test/Semantics/OpenMP/resolve05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! 2.15.3 Data-Sharing Attribute Clauses
diff --git a/flang/test/Semantics/OpenMP/resolve06.f90 b/flang/test/Semantics/OpenMP/resolve06.f90
index f972905005595..2859ce2b690fb 100644
--- a/flang/test/Semantics/OpenMP/resolve06.f90
+++ b/flang/test/Semantics/OpenMP/resolve06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/sections01.f90 b/flang/test/Semantics/OpenMP/sections01.f90
index c26cc88dcc7af..00b5a6d8fbc4c 100644
--- a/flang/test/Semantics/OpenMP/sections01.f90
+++ b/flang/test/Semantics/OpenMP/sections01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/sections02.f90 b/flang/test/Semantics/OpenMP/sections02.f90
index b96455a960ef8..5a563c71dcc2a 100644
--- a/flang/test/Semantics/OpenMP/sections02.f90
+++ b/flang/test/Semantics/OpenMP/sections02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
diff --git a/flang/test/Semantics/OpenMP/sections03.f90 b/flang/test/Semantics/OpenMP/sections03.f90
index 69775013ea823..b170f8674d19d 100644
--- a/flang/test/Semantics/OpenMP/sections03.f90
+++ b/flang/test/Semantics/OpenMP/sections03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 !XFAIL: *
 ! OpenMP version 5.0.0
diff --git a/flang/test/Semantics/OpenMP/simd-aligned.f90 b/flang/test/Semantics/OpenMP/simd-aligned.f90
index 0a9f95833e22e..3ffdc68693fd9 100644
--- a/flang/test/Semantics/OpenMP/simd-aligned.f90
+++ b/flang/test/Semantics/OpenMP/simd-aligned.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/simd-nontemporal.f90 b/flang/test/Semantics/OpenMP/simd-nontemporal.f90
index a488edd98cdc3..074b0a2039edc 100644
--- a/flang/test/Semantics/OpenMP/simd-nontemporal.f90
+++ b/flang/test/Semantics/OpenMP/simd-nontemporal.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/simd01.f90 b/flang/test/Semantics/OpenMP/simd01.f90
index 1aa2880cda831..1e241648f75a2 100644
--- a/flang/test/Semantics/OpenMP/simd01.f90
+++ b/flang/test/Semantics/OpenMP/simd01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 5.0
 ! 2.9.3.1 simd Construct
diff --git a/flang/test/Semantics/OpenMP/simd02.f90 b/flang/test/Semantics/OpenMP/simd02.f90
index a627e2ac2d67c..24d6abd9761fc 100644
--- a/flang/test/Semantics/OpenMP/simd02.f90
+++ b/flang/test/Semantics/OpenMP/simd02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 4.5
diff --git a/flang/test/Semantics/OpenMP/simd03.f90 b/flang/test/Semantics/OpenMP/simd03.f90
index 38f45da47748f..8df48368fa969 100644
--- a/flang/test/Semantics/OpenMP/simd03.f90
+++ b/flang/test/Semantics/OpenMP/simd03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %S/test_errors.sh %s %t %flang -fopenmp
 ! XFAIL: *
 
diff --git a/flang/test/Semantics/OpenMP/single01.f90 b/flang/test/Semantics/OpenMP/single01.f90
index 2e40bec56e9c2..0468e695d8cf0 100644
--- a/flang/test/Semantics/OpenMP/single01.f90
+++ b/flang/test/Semantics/OpenMP/single01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.3 single Construct
diff --git a/flang/test/Semantics/OpenMP/single02.f90 b/flang/test/Semantics/OpenMP/single02.f90
index 03cf7fbb6ad38..9d9d306c2f532 100644
--- a/flang/test/Semantics/OpenMP/single02.f90
+++ b/flang/test/Semantics/OpenMP/single02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.3 single Construct
diff --git a/flang/test/Semantics/OpenMP/struct.f90 b/flang/test/Semantics/OpenMP/struct.f90
index 8ae1fbe4da86f..3d2000aef9931 100644
--- a/flang/test/Semantics/OpenMP/struct.f90
+++ b/flang/test/Semantics/OpenMP/struct.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! Check OpenMP compatibility with the DEC STRUCTURE extension
 
diff --git a/flang/test/Semantics/OpenMP/symbol01.f90 b/flang/test/Semantics/OpenMP/symbol01.f90
index 0b435a9ab9850..e2a9c01e9d5f2 100644
--- a/flang/test/Semantics/OpenMP/symbol01.f90
+++ b/flang/test/Semantics/OpenMP/symbol01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! Test clauses that accept list.
diff --git a/flang/test/Semantics/OpenMP/symbol02.f90 b/flang/test/Semantics/OpenMP/symbol02.f90
index f6ffc5500d0a4..1b1dc44894488 100644
--- a/flang/test/Semantics/OpenMP/symbol02.f90
+++ b/flang/test/Semantics/OpenMP/symbol02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! 1.4.1 Structure of the OpenMP Memory Model
diff --git a/flang/test/Semantics/OpenMP/symbol03.f90 b/flang/test/Semantics/OpenMP/symbol03.f90
index 93e9b7a3eae6b..76d93577d3ace 100644
--- a/flang/test/Semantics/OpenMP/symbol03.f90
+++ b/flang/test/Semantics/OpenMP/symbol03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! 1.4.1 Structure of the OpenMP Memory Model
diff --git a/flang/test/Semantics/OpenMP/symbol04.f90 b/flang/test/Semantics/OpenMP/symbol04.f90
index 808d1e0dd09be..8ef154ebbf9d7 100644
--- a/flang/test/Semantics/OpenMP/symbol04.f90
+++ b/flang/test/Semantics/OpenMP/symbol04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! 2.15.3 Data-Sharing Attribute Clauses
diff --git a/flang/test/Semantics/OpenMP/symbol05.f90 b/flang/test/Semantics/OpenMP/symbol05.f90
index fa0a8f65a4294..d08d85270380e 100644
--- a/flang/test/Semantics/OpenMP/symbol05.f90
+++ b/flang/test/Semantics/OpenMP/symbol05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! 2.15.2 threadprivate Directive
diff --git a/flang/test/Semantics/OpenMP/symbol06.f90 b/flang/test/Semantics/OpenMP/symbol06.f90
index 906264eb12642..a2cd288dfd15f 100644
--- a/flang/test/Semantics/OpenMP/symbol06.f90
+++ b/flang/test/Semantics/OpenMP/symbol06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! 2.15.3 Data-Sharing Attribute Clauses
diff --git a/flang/test/Semantics/OpenMP/symbol07.f90 b/flang/test/Semantics/OpenMP/symbol07.f90
index e2250f5c7908a..ee6cd2a0df2ee 100644
--- a/flang/test/Semantics/OpenMP/symbol07.f90
+++ b/flang/test/Semantics/OpenMP/symbol07.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! Generic tests
diff --git a/flang/test/Semantics/OpenMP/symbol08.f90 b/flang/test/Semantics/OpenMP/symbol08.f90
index 3af85af74ee97..76db86cd54caa 100644
--- a/flang/test/Semantics/OpenMP/symbol08.f90
+++ b/flang/test/Semantics/OpenMP/symbol08.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! 2.15.1.1 Predetermined rules for associated do-loops index variable
diff --git a/flang/test/Semantics/OpenMP/symbol09.f90 b/flang/test/Semantics/OpenMP/symbol09.f90
index e2250f5c7908a..ee6cd2a0df2ee 100644
--- a/flang/test/Semantics/OpenMP/symbol09.f90
+++ b/flang/test/Semantics/OpenMP/symbol09.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_symbols.py %s %flang_fc1 -fopenmp
 
 ! Generic tests
diff --git a/flang/test/Semantics/OpenMP/sync-critical01.f90 b/flang/test/Semantics/OpenMP/sync-critical01.f90
index b597eb17ea226..ef377ebc72f2b 100644
--- a/flang/test/Semantics/OpenMP/sync-critical01.f90
+++ b/flang/test/Semantics/OpenMP/sync-critical01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 5.0
diff --git a/flang/test/Semantics/OpenMP/sync-critical02.f90 b/flang/test/Semantics/OpenMP/sync-critical02.f90
index fdd95fa76ad7c..f4090267e790a 100644
--- a/flang/test/Semantics/OpenMP/sync-critical02.f90
+++ b/flang/test/Semantics/OpenMP/sync-critical02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
diff --git a/flang/test/Semantics/OpenMP/target-update01.f90 b/flang/test/Semantics/OpenMP/target-update01.f90
index 84dc60dcd75f5..706d0ba8bafb4 100644
--- a/flang/test/Semantics/OpenMP/target-update01.f90
+++ b/flang/test/Semantics/OpenMP/target-update01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 
 subroutine foo(x)
diff --git a/flang/test/Semantics/OpenMP/target.f90 b/flang/test/Semantics/OpenMP/target.f90
index 994c04048edff..b98d27192ac9b 100644
--- a/flang/test/Semantics/OpenMP/target.f90
+++ b/flang/test/Semantics/OpenMP/target.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp -Werror
 
 ! Corner cases in OpenMP target directives
diff --git a/flang/test/Semantics/OpenMP/target01.f90 b/flang/test/Semantics/OpenMP/target01.f90
index 9836f0112738f..2da7ab5c9b100 100644
--- a/flang/test/Semantics/OpenMP/target01.f90
+++ b/flang/test/Semantics/OpenMP/target01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 
 subroutine foo(b)
diff --git a/flang/test/Semantics/OpenMP/target02.f90 b/flang/test/Semantics/OpenMP/target02.f90
index 06ce1c0875cc9..82b8ca1a430e7 100644
--- a/flang/test/Semantics/OpenMP/target02.f90
+++ b/flang/test/Semantics/OpenMP/target02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 4.5
 
diff --git a/flang/test/Semantics/OpenMP/task01.f90 b/flang/test/Semantics/OpenMP/task01.f90
index 4dc80d6d70e05..de4321ebc5785 100644
--- a/flang/test/Semantics/OpenMP/task01.f90
+++ b/flang/test/Semantics/OpenMP/task01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: not %flang -fsyntax-only -fopenmp %s 2>&1 | FileCheck %s
 ! OpenMP Version 4.5
 ! 2.9.1 task Construct
diff --git a/flang/test/Semantics/OpenMP/taskgroup01.f90 b/flang/test/Semantics/OpenMP/taskgroup01.f90
index e3185552a44bb..b0c3215adc65a 100644
--- a/flang/test/Semantics/OpenMP/taskgroup01.f90
+++ b/flang/test/Semantics/OpenMP/taskgroup01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
@@ -47,4 +49,4 @@
       !$omp end taskgroup
     !$omp end task
   !$omp end parallel
-end program
\ No newline at end of file
+end program
diff --git a/flang/test/Semantics/OpenMP/taskloop-simd01.f90 b/flang/test/Semantics/OpenMP/taskloop-simd01.f90
index bb7266a52f61e..6316b9629cf38 100644
--- a/flang/test/Semantics/OpenMP/taskloop-simd01.f90
+++ b/flang/test/Semantics/OpenMP/taskloop-simd01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 ! OpenMP Version 5.0
diff --git a/flang/test/Semantics/OpenMP/taskloop01.f90 b/flang/test/Semantics/OpenMP/taskloop01.f90
index 6bef584381518..2c53759494048 100644
--- a/flang/test/Semantics/OpenMP/taskloop01.f90
+++ b/flang/test/Semantics/OpenMP/taskloop01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.9.2 taskloop Construct
diff --git a/flang/test/Semantics/OpenMP/taskloop02.f90 b/flang/test/Semantics/OpenMP/taskloop02.f90
index 867ef8a9806d9..275b079d38a1e 100644
--- a/flang/test/Semantics/OpenMP/taskloop02.f90
+++ b/flang/test/Semantics/OpenMP/taskloop02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: not %flang -fsyntax-only -fopenmp %s 2>&1 | FileCheck %s
 ! OpenMP Version 4.5
 ! 2.9.2 taskloop Construct
diff --git a/flang/test/Semantics/OpenMP/taskloop03.f90 b/flang/test/Semantics/OpenMP/taskloop03.f90
deleted file mode 100644
index 7e2e426a3fe7e..0000000000000
--- a/flang/test/Semantics/OpenMP/taskloop03.f90
+++ /dev/null
@@ -1,25 +0,0 @@
-! RUN: %S/test_errors.sh %s %t %flang -fopenmp
-! XFAIL: *
-
-! OpenMP Version 4.5
-! 2.9.2 taskloop Construct
-! All loops associated with the taskloop construct must be perfectly nested,
-! there must be no intervening code or any OpenMP directive between
-! any two loops
-
-program omp_taskloop
-  integer i, j
-
-  !$omp taskloop private(j) grainsize(500) nogroup
-  do i=1, 10000
-    do j=1, i
-      call loop_body(i, j)
-    end do
-    !ERROR: Loops associated with !$omp taskloop is not perfectly nested
-    !$omp single
-    print *, "omp single"
-    !$omp end single
-  end do
-  !$omp end taskloop
-
-end program omp_taskloop
diff --git a/flang/test/Semantics/OpenMP/taskwait.f90 b/flang/test/Semantics/OpenMP/taskwait.f90
index e60051c9da8ac..a3b15c7a1df0a 100644
--- a/flang/test/Semantics/OpenMP/taskwait.f90
+++ b/flang/test/Semantics/OpenMP/taskwait.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 
 !$omp taskwait
diff --git a/flang/test/Semantics/OpenMP/threadprivate01.f90 b/flang/test/Semantics/OpenMP/threadprivate01.f90
index 5ba5f400eb203..d0d6990215180 100644
--- a/flang/test/Semantics/OpenMP/threadprivate01.f90
+++ b/flang/test/Semantics/OpenMP/threadprivate01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! REQUIRES: openmp_runtime
 
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
diff --git a/flang/test/Semantics/OpenMP/threadprivate02.f90 b/flang/test/Semantics/OpenMP/threadprivate02.f90
index 7f6e8dcc8e8ab..862d1e8a45c42 100644
--- a/flang/test/Semantics/OpenMP/threadprivate02.f90
+++ b/flang/test/Semantics/OpenMP/threadprivate02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/threadprivate03.f90 b/flang/test/Semantics/OpenMP/threadprivate03.f90
index b466a8e05e9c2..57d3b9209820c 100644
--- a/flang/test/Semantics/OpenMP/threadprivate03.f90
+++ b/flang/test/Semantics/OpenMP/threadprivate03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp -pedantic
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/threadprivate04.f90 b/flang/test/Semantics/OpenMP/threadprivate04.f90
index 3d8c7fb8de8fa..8199dbaea166c 100644
--- a/flang/test/Semantics/OpenMP/threadprivate04.f90
+++ b/flang/test/Semantics/OpenMP/threadprivate04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/threadprivate05.f90 b/flang/test/Semantics/OpenMP/threadprivate05.f90
index cdbf3701b70ae..eecf9e781cf71 100644
--- a/flang/test/Semantics/OpenMP/threadprivate05.f90
+++ b/flang/test/Semantics/OpenMP/threadprivate05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/threadprivate06.f90 b/flang/test/Semantics/OpenMP/threadprivate06.f90
index f31c38f6f2b24..5537a8805e9fb 100644
--- a/flang/test/Semantics/OpenMP/threadprivate06.f90
+++ b/flang/test/Semantics/OpenMP/threadprivate06.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.1
 ! Check OpenMP construct validity for the following directives:
diff --git a/flang/test/Semantics/OpenMP/threadprivate07.f90 b/flang/test/Semantics/OpenMP/threadprivate07.f90
index c9a006ca0e083..5302fdf4ab718 100644
--- a/flang/test/Semantics/OpenMP/threadprivate07.f90
+++ b/flang/test/Semantics/OpenMP/threadprivate07.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 
 ! Check Threadprivate Directive with local variable of a BLOCK construct.
diff --git a/flang/test/Semantics/OpenMP/use_device_addr.f90 b/flang/test/Semantics/OpenMP/use_device_addr.f90
index 93a7643b5eb48..dda00d5105043 100644
--- a/flang/test/Semantics/OpenMP/use_device_addr.f90
+++ b/flang/test/Semantics/OpenMP/use_device_addr.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-symbols %s | FileCheck %s
 ! OpenMP Version 5.1
 ! 2.14.2 use_device_addr clause
diff --git a/flang/test/Semantics/OpenMP/use_device_addr1.f90 b/flang/test/Semantics/OpenMP/use_device_addr1.f90
index 867e324b68ad9..c37e9a3a7e3ee 100644
--- a/flang/test/Semantics/OpenMP/use_device_addr1.f90
+++ b/flang/test/Semantics/OpenMP/use_device_addr1.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.0
 ! 2.10.1 use_device_ptr clause
diff --git a/flang/test/Semantics/OpenMP/use_device_ptr.f90 b/flang/test/Semantics/OpenMP/use_device_ptr.f90
index 64b98cf67961d..e9e7fbb6c1f5b 100644
--- a/flang/test/Semantics/OpenMP/use_device_ptr.f90
+++ b/flang/test/Semantics/OpenMP/use_device_ptr.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %flang_fc1 -fopenmp -fdebug-dump-symbols %s | FileCheck %s
 ! OpenMP Version 5.0
 ! 2.10.1 use_device_ptr clause
diff --git a/flang/test/Semantics/OpenMP/use_device_ptr1.f90 b/flang/test/Semantics/OpenMP/use_device_ptr1.f90
index 176fb5f35a849..f705c50370dae 100644
--- a/flang/test/Semantics/OpenMP/use_device_ptr1.f90
+++ b/flang/test/Semantics/OpenMP/use_device_ptr1.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
 ! OpenMP Version 5.0
 ! 2.10.1 use_device_ptr clause
diff --git a/flang/test/Semantics/OpenMP/workshare01.f90 b/flang/test/Semantics/OpenMP/workshare01.f90
index 9667a306061c0..615c3408dc7ae 100644
--- a/flang/test/Semantics/OpenMP/workshare01.f90
+++ b/flang/test/Semantics/OpenMP/workshare01.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.4 workshare Construct
diff --git a/flang/test/Semantics/OpenMP/workshare02.f90 b/flang/test/Semantics/OpenMP/workshare02.f90
index e099ecb9f1e61..b6faf197f1f2e 100644
--- a/flang/test/Semantics/OpenMP/workshare02.f90
+++ b/flang/test/Semantics/OpenMP/workshare02.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.4 workshare Construct
diff --git a/flang/test/Semantics/OpenMP/workshare03.f90 b/flang/test/Semantics/OpenMP/workshare03.f90
index 09d46abf42eec..2aea0ccce3c72 100644
--- a/flang/test/Semantics/OpenMP/workshare03.f90
+++ b/flang/test/Semantics/OpenMP/workshare03.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.4 workshare Construct
diff --git a/flang/test/Semantics/OpenMP/workshare04.f90 b/flang/test/Semantics/OpenMP/workshare04.f90
index 0ec635e52d2b7..e84459978e15e 100644
--- a/flang/test/Semantics/OpenMP/workshare04.f90
+++ b/flang/test/Semantics/OpenMP/workshare04.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.4 workshare Construct
diff --git a/flang/test/Semantics/OpenMP/workshare05.f90 b/flang/test/Semantics/OpenMP/workshare05.f90
index b57053e092e67..30f3b988de915 100644
--- a/flang/test/Semantics/OpenMP/workshare05.f90
+++ b/flang/test/Semantics/OpenMP/workshare05.f90
@@ -1,3 +1,5 @@
+! UNSUPPORTED: system-windows
+! Marking as unsupported due to suspected long runtime on Windows
 ! RUN: %python %S/../test_errors.py %s %flang -fopenmp
 ! OpenMP Version 4.5
 ! 2.7.4 workshare Construct