diff --git a/.ci/generate-buildkite-pipeline-premerge b/.ci/generate-buildkite-pipeline-premerge
index 3ed5eb96eceb5..bb7d2117e277f 100755
--- a/.ci/generate-buildkite-pipeline-premerge
+++ b/.ci/generate-buildkite-pipeline-premerge
@@ -53,7 +53,10 @@ echo "Directories modified:" >&2
 echo "$modified_dirs" >&2
 
 function compute-projects-to-test() {
+  isForWindows=$1
+  shift
   projects=${@}
+  echo "isForWindows : $isForWindows ; projects: $projects " >&2
   for project in ${projects}; do
     echo "${project}"
     case ${project} in
@@ -63,9 +66,13 @@ function compute-projects-to-test() {
       done
     ;;
     llvm)
-      for p in bolt clang clang-tools-extra flang lld lldb mlir polly; do
+      for p in bolt clang clang-tools-extra lld lldb mlir polly; do
         echo $p
       done
+      # Flang is not stable in Windows CI at the moment
+      if [[ $isForWindows == 0 ]]; then
+        echo flang
+      fi
     ;;
     clang)
       for p in clang-tools-extra compiler-rt lldb cross-project-tests; do
@@ -76,7 +83,10 @@ function compute-projects-to-test() {
       echo libc
     ;;
     mlir)
-      echo flang
+      # Flang is not stable in Windows CI at the moment
+      if [[ $isForWindows == 0 ]]; then
+        echo flang
+      fi
     ;;
     *)
       # Nothing to do
@@ -241,7 +251,7 @@ fi
 all_projects="bolt clang clang-tools-extra compiler-rt cross-project-tests flang libc libclc lld lldb llvm mlir openmp polly pstl"
 modified_projects="$(keep-modified-projects ${all_projects})"
 
-linux_projects_to_test=$(exclude-linux $(compute-projects-to-test ${modified_projects}))
+linux_projects_to_test=$(exclude-linux $(compute-projects-to-test 0 ${modified_projects}))
 linux_check_targets=$(check-targets ${linux_projects_to_test} | sort | uniq)
 linux_projects=$(add-dependencies ${linux_projects_to_test} | sort | uniq)
 
@@ -249,7 +259,7 @@ linux_runtimes_to_test=$(compute-runtimes-to-test ${linux_projects_to_test})
 linux_runtime_check_targets=$(check-targets ${linux_runtimes_to_test} | sort | uniq)
 linux_runtimes=$(echo ${linux_runtimes_to_test} | sort | uniq)
 
-windows_projects_to_test=$(exclude-windows $(compute-projects-to-test ${modified_projects}))
+windows_projects_to_test=$(exclude-windows $(compute-projects-to-test 1 ${modified_projects}))
 windows_check_targets=$(check-targets ${windows_projects_to_test} | sort | uniq)
 windows_projects=$(add-dependencies ${windows_projects_to_test} | sort | uniq)