diff --git a/test/configs/apple-libc++abi-backdeployment.cfg.in b/test/configs/apple-libc++abi-backdeployment.cfg.in
index 9239c55..06dd503 100644
--- a/test/configs/apple-libc++abi-backdeployment.cfg.in
+++ b/test/configs/apple-libc++abi-backdeployment.cfg.in
@@ -45,7 +45,7 @@
     '-isysroot {}'.format('@CMAKE_OSX_SYSROOT@') if '@CMAKE_OSX_SYSROOT@' else ''
 ))
 config.substitutions.append(('%{compile_flags}',
-    '-nostdinc++ -isystem %{install}/include/c++/v1 -DLIBCXXABI_NO_TIMER -D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS ' +
+    '-nostdinc++ -I %{install}/include/c++/v1 -DLIBCXXABI_NO_TIMER -D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS ' +
     '-I %{libcxx}/test/support -I %{libcxx}/src'
 ))
 config.substitutions.append(('%{link_flags}',
diff --git a/test/configs/apple-libc++abi-shared.cfg.in b/test/configs/apple-libc++abi-shared.cfg.in
index 4d0df23..cf65ce4 100644
--- a/test/configs/apple-libc++abi-shared.cfg.in
+++ b/test/configs/apple-libc++abi-shared.cfg.in
@@ -6,7 +6,7 @@
     '-isysroot {}'.format('@CMAKE_OSX_SYSROOT@') if '@CMAKE_OSX_SYSROOT@' else ''
 ))
 config.substitutions.append(('%{compile_flags}',
-    '-nostdinc++ -isystem %{install}/include/c++/v1 -DLIBCXXABI_NO_TIMER -D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS ' +
+    '-nostdinc++ -I %{install}/include/c++/v1 -DLIBCXXABI_NO_TIMER -D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS ' +
     '-I %{libcxx}/test/support -I %{libcxx}/src'
 ))
 config.substitutions.append(('%{link_flags}',
diff --git a/test/configs/ibm-libc++abi-shared.cfg.in b/test/configs/ibm-libc++abi-shared.cfg.in
index 06d9aca..64fc4f2 100644
--- a/test/configs/ibm-libc++abi-shared.cfg.in
+++ b/test/configs/ibm-libc++abi-shared.cfg.in
@@ -4,7 +4,7 @@
 
 config.substitutions.append(('%{flags}',''))
 config.substitutions.append(('%{compile_flags}',
-    '-nostdinc++ -isystem %{install}/include/c++/v1 ' + 
+    '-nostdinc++ -I %{install}/include/c++/v1 ' +
     '-D__LIBC_NO_CPP_MATH_OVERLOADS__ -DLIBCXXABI_NO_TIMER ' +
     '-D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS ' +
     '-I %{libcxx}/test/support -I %{libcxx}/src'