diff --git a/.circleci/config.yml b/.circleci/config.yml
index 15edef8f77d..c6127678a53 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -4,6 +4,7 @@ commonSteps: &commonSteps
     - run:
         name: Install dependencies
         command: |
+          set -x
           cd ..
           if [ "$CI_OS" = "linux" ]; then
             export DEBIAN_FRONTEND=noninteractive
@@ -25,25 +26,31 @@ commonSteps: &commonSteps
           else
             # install libconfig
             brew install libconfig
-            # install CMake
-            curl -L -o cmake-x64.tar.gz https://cmake.org/files/v3.10/cmake-3.10.0-Darwin-x86_64.tar.gz
-            mkdir cmake-x64
-            tar -xf cmake-x64.tar.gz --strip 3 -C cmake-x64
-            # install Ninja
-            curl -OL https://github.com/ninja-build/ninja/releases/download/v1.8.2/ninja-mac.zip
+            # Download & extract CMake
+            curl -L -o cmake.tar.gz https://github.com/Kitware/CMake/releases/download/v3.13.4/cmake-3.13.4-Darwin-x86_64.tar.gz
+            mkdir cmake
+            tar -xf cmake.tar.gz --strip 3 -C cmake
+            rm cmake.tar.gz
+            # Download & extract Ninja
+            curl -OL https://github.com/ninja-build/ninja/releases/download/v1.9.0/ninja-mac.zip
             mkdir ninja
             tar -xf ninja-mac.zip -C ninja
-            echo "export PATH=$PWD/cmake-x64/bin:$PWD/ninja:$PATH" >> $BASH_ENV
-            # install Python pip
+            rm ninja-mac.zip
+            # Install pip
             curl -OL https://bootstrap.pypa.io/get-pip.py
-            python get-pip.py
+            python get-pip.py --user
+            rm get-pip.py
+            # Add CMake and Ninja to PATH for future steps
+            echo "export PATH=$PWD/cmake/bin:$PWD/ninja:$PATH" >> $BASH_ENV
           fi
-          # install lit
-          pip install --user lit
+          # Install lit
+          python -m pip install --user lit
+          python -c "import lit; lit.main();" --version | head -n 1
     - checkout
     - run:
         name: Install LDC-flavoured LLVM
         command: |
+          set -x
           cd ..
           mkdir llvm-$LLVM_VERSION
           assertsSuffix=""
@@ -60,6 +67,7 @@ commonSteps: &commonSteps
     - run:
         name: Build LDC
         command: |
+          set -x
           cd ..
           LDC_INSTALL_DIR=$PWD/ldc2-x64
           mkdir ninja-ldc
@@ -72,6 +80,7 @@ commonSteps: &commonSteps
         name: Build stdlib unittests
         when: always
         command: |
+          set -x
           cd ../ninja-ldc
           ninja -j2 phobos2-ldc-unittest-debug phobos2-ldc-unittest phobos2-ldc-unittest-debug-32 phobos2-ldc-unittest-32
           ninja -j3 druntime-ldc-unittest-debug druntime-ldc-unittest druntime-ldc-unittest-debug-32 druntime-ldc-unittest-32
@@ -84,6 +93,7 @@ commonSteps: &commonSteps
         name: Run DMD testsuite
         when: always
         command: |
+          set -x
           cd ../ninja-ldc
           if [ "$CI_OS" = "linux" ]; then
             # runnable/{sdtor,variadic} fail, see https://github.com/ldc-developers/ldc/pull/2825#issuecomment-415527889
@@ -95,6 +105,7 @@ commonSteps: &commonSteps
         name: Run stdlib unittests
         when: always
         command: |
+          set -x
           cd ../ninja-ldc
           if [ "$CI_OS" = "osx" ]; then
             # 32-bit std.process unittests fail; exclude for now
@@ -106,6 +117,7 @@ commonSteps: &commonSteps
     - run:
         name: Install LDC
         command: |
+          set -x
           cd ../ninja-ldc
           ninja install
           cd ..
@@ -124,6 +136,7 @@ commonSteps: &commonSteps
     - run:
         name: Build dub
         command: |
+          set -x
           cd ..
           export DMD=$LDC_INSTALL_DIR/bin/ldmd2
           git clone --recursive https://github.com/dlang/dub.git
@@ -140,6 +153,7 @@ commonSteps: &commonSteps
     - run:
         name: Pack installation dir
         command: |
+          set -x
           cd ..
           mkdir artifacts
           if [ -z "$CIRCLE_TAG" ]; then
@@ -152,6 +166,7 @@ commonSteps: &commonSteps
     - run:
         name: Pack source dir
         command: |
+          set -x
           cd ..
           if [ "$CI_OS" = "linux" ]; then
             if [ -z "$CIRCLE_TAG" ]; then
@@ -168,6 +183,7 @@ commonSteps: &commonSteps
     - run:
         name: Deploy to GitHub release if tagged
         command: |
+          set -x
           cd ..
           if [[ -n "$CIRCLE_TAG" ]]; then
             if [ "$CI_OS" = "linux" ]; then
@@ -199,10 +215,10 @@ jobs:
   build-osx:
     <<: *commonSteps
     macos:
-      xcode: "9.2.0"
+      xcode: "11.4.0"
     environment:
       - CI_OS: osx
-      - MACOSX_DEPLOYMENT_TARGET: 10.8
+      - MACOSX_DEPLOYMENT_TARGET: 10.9
       - USE_LIBCPP: true
       - LLVM_VERSION: 6.0.1-3
       - EXTRA_CMAKE_FLAGS: "-DMULTILIB=ON -DBUILD_SHARED_LIBS=OFF -DCMAKE_CXX_FLAGS='-stdlib=libc++' -DCMAKE_EXE_LINKER_FLAGS=-lc++"
diff --git a/runtime/druntime b/runtime/druntime
index 13b1ccf572e..8154456755c 160000
--- a/runtime/druntime
+++ b/runtime/druntime
@@ -1 +1 @@
-Subproject commit 13b1ccf572ed281b7f59222c6126d3aba0ca1ff1
+Subproject commit 8154456755cc77724993b5ca7c8e90be4a107b58