diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a8d9f64f85..cc105292b1 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -27,6 +27,7 @@ jobs:
           - job_name: Ubuntu 22.04 x64, DMD (bootstrap)
             os: ubuntu-22.04
             host_dmd: dmd-2.079.0
+            disable_debug_for_dmd_unittests: true # no `-debug` - host frontend too old
           - job_name: Ubuntu 22.04 x86, DMD (latest)
             os: ubuntu-22.04
             model: 32
@@ -46,6 +47,7 @@ jobs:
           - job_name: Ubuntu 22.04 x64, GDC
             os: ubuntu-22.04
             host_dmd: gdmd-9
+            disable_debug_for_dmd_unittests: true # no `-debug` - host frontend too old
           # macOS
           - job_name: macOS 13 x64, DMD (latest)
             os: macos-13
@@ -64,13 +66,15 @@ jobs:
     timeout-minutes: 40
     env:
       # for ci/run.sh:
-      OS_NAME: ${{ startsWith(matrix.os, 'ubuntu') && 'linux' || (startsWith(matrix.os, 'macos') && 'darwin' || '') }}
+      OS_NAME: ${{ startsWith(matrix.os, 'ubuntu') && 'linux' || (startsWith(matrix.os, 'macos') && 'osx' || '') }}
       MODEL: ${{ matrix.model || '64' }}
       HOST_DMD: ${{ matrix.host_dmd }}
       N: ${{ startsWith(matrix.os, 'macos') && '3' || '2' }}
       FULL_BUILD: true
       # for coverage:
       DMD_TEST_COVERAGE: ${{ matrix.coverage && '1' || '0' }}
+      # work around https://issues.dlang.org/show_bug.cgi?id=23517
+      MACOSX_DEPLOYMENT_TARGET: '11'
     steps:
       - uses: actions/checkout@v4
         with:
@@ -99,10 +103,10 @@ jobs:
 
           ci/run.sh setup_repos "$REPO_BRANCH"
       - name: Build
-        run: ci/run.sh build
+        run: ${{ matrix.disable_debug_for_dmd_unittests && 'ENABLE_DEBUG=0' || '' }} ci/run.sh build
       - name: Rebuild dmd (with enabled coverage)
         if: matrix.coverage
-        run: ENABLE_RELEASE=0 ENABLE_DEBUG=1 ENABLE_COVERAGE=1 ${{ runner.os == 'macOS' && 'OS_NAME=osx' || '' }} ci/run.sh rebuild
+        run: ENABLE_RELEASE=0 ENABLE_DEBUG=1 ENABLE_COVERAGE=1 ci/run.sh rebuild
       - name: Test dmd
         run: ci/run.sh test_dmd
       - name: Test druntime
diff --git a/ci/cirrusci.sh b/ci/cirrusci.sh
index 157051819c..b8c3886eee 100755
--- a/ci/cirrusci.sh
+++ b/ci/cirrusci.sh
@@ -6,7 +6,7 @@
 
 set -uexo pipefail
 
-# OS_NAME: linux|darwin|freebsd
+# OS_NAME: linux|osx|freebsd
 if [ -z ${OS_NAME+x} ] ; then echo "Variable 'OS_NAME' needs to be set."; exit 1; fi
 # MODEL: 32|64
 if [ -z ${MODEL+x} ] ; then echo "Variable 'MODEL' needs to be set."; exit 1; fi
@@ -27,7 +27,7 @@ if [ "$OS_NAME" == "linux" ]; then
   fi
   apt-get -q update
   apt-get install -yq $packages
-elif [ "$OS_NAME" == "darwin" ]; then
+elif [ "$OS_NAME" == "osx" ]; then
   # required for dlang install.sh
   brew install gnupg libarchive xz llvm
 elif [ "$OS_NAME" == "freebsd" ]; then
diff --git a/ci/run.sh b/ci/run.sh
index c9f5ed34b9..79834769c1 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -7,7 +7,7 @@ set -uexo pipefail
 
 # N: number of parallel build jobs
 if [ -z ${N+x} ] ; then echo "Variable 'N' needs to be set."; exit 1; fi
-# OS_NAME: linux|darwin|freebsd
+# OS_NAME: linux|osx|freebsd
 if [ -z ${OS_NAME+x} ] ; then echo "Variable 'OS_NAME' needs to be set."; exit 1; fi
 # FULL_BUILD: true|false (true on Linux: use full permutations for DMD tests)
 if [ -z ${FULL_BUILD+x} ] ; then echo "Variable 'FULL_BUILD' needs to be set."; exit 1; fi
@@ -34,7 +34,7 @@ if [ "$OS_NAME" == "linux" ]; then
 else
     NM=nm
 
-  if [ "$OS_NAME" == "darwin" ]; then
+  if [ "$OS_NAME" == "osx" ]; then
     export PATH="/usr/local/opt/llvm/bin:$PATH"
   fi
 fi
@@ -59,8 +59,9 @@ clone() {
 # build dmd (incl. building and running the unittests), druntime, phobos
 build() {
     source ~/dlang/*/activate # activate host compiler, incl. setting `DMD`
-    make -j$N -C compiler/src -f posix.mak MODEL=$MODEL HOST_DMD=$DMD DFLAGS="$CI_DFLAGS" BUILD=debug ENABLE_WARNINGS=1 unittest
-    make -j$N -C compiler/src -f posix.mak MODEL=$MODEL HOST_DMD=$DMD DFLAGS="$CI_DFLAGS" ENABLE_RELEASE=1 ENABLE_WARNINGS=1 all
+    $DMD compiler/src/build.d -ofgenerated/build
+    generated/build -j$N MODEL=$MODEL HOST_DMD=$DMD DFLAGS="$CI_DFLAGS" BUILD=debug unittest
+    generated/build -j$N MODEL=$MODEL HOST_DMD=$DMD DFLAGS="$CI_DFLAGS" ENABLE_RELEASE=1 dmd
     make -j$N -C druntime -f posix.mak MODEL=$MODEL
     make -j$N -C ../phobos -f posix.mak MODEL=$MODEL
     deactivate # deactivate host compiler
@@ -75,8 +76,8 @@ rebuild() {
     mkdir -p _${build_path}
     cp $build_path/dmd _${build_path}/host_dmd
     cp $build_path/dmd.conf _${build_path}
-    make -j$N -C compiler/src -f posix.mak MODEL=$MODEL HOST_DMD=../../_${build_path}/host_dmd clean
-    make -j$N -C compiler/src -f posix.mak MODEL=$MODEL HOST_DMD=../../_${build_path}/host_dmd DFLAGS="$CI_DFLAGS" ENABLE_RELEASE=${ENABLE_RELEASE:-1} ENABLE_WARNINGS=1 all
+    rm -rf $build_path
+    generated/build -j$N MODEL=$MODEL HOST_DMD=_${build_path}/host_dmd DFLAGS="$CI_DFLAGS" ENABLE_RELEASE=${ENABLE_RELEASE:-1} dmd
 
     # compare binaries to test reproducible build
     if [ $compare -eq 1 ]; then
@@ -100,12 +101,15 @@ test() {
 
 # test dmd
 test_dmd() {
-    # test fewer compiler argument permutations for PRs to reduce CI load
-    if [ "$FULL_BUILD" == "true" ] && [ "$OS_NAME" == "linux"  ]; then
-        make -j1 -C compiler/test MODEL=$MODEL N=$N # all ARGS by default
+    # default to testing fewer compiler argument permutations to reduce CI load
+    if [ "$FULL_BUILD" == "true" ] && [ "$OS_NAME" == "linux" ]; then
+        local args=() # use all default ARGS
     else
-        make -j1 -C compiler/test MODEL=$MODEL N=$N ARGS="-O -inline -release"
+        local args=(ARGS="-O -inline -release")
     fi
+
+    $build_path/dmd -g -i -Icompiler/test -release compiler/test/run.d -ofgenerated/run
+    generated/run -j$N --environment MODEL=$MODEL HOST_DMD=$build_path/dmd "${args[@]}"
 }
 
 # build and run druntime unit tests