diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
--- a/runtimes/CMakeLists.txt
+++ b/runtimes/CMakeLists.txt
@@ -9,6 +9,17 @@
   set(LLVM_ENABLE_RUNTIMES ${LLVM_ALL_RUNTIMES})
 endif()
 
+# If both libc++ and libc++abi are being built, always configure libc++abi before libc++.
+# This allows libc++ to depend on targets set up by libc++abi when it needs to.
+if (libcxx IN_LIST LLVM_ENABLE_RUNTIMES AND libcxxabi IN_LIST LLVM_ENABLE_RUNTIMES)
+  list(FIND LLVM_ENABLE_RUNTIMES libcxx _libcxx_index)
+  list(FIND LLVM_ENABLE_RUNTIMES libcxxabi _libcxxabi_index)
+  if (_libcxx_index LESS _libcxxabi_index)
+    list(TRANSFORM LLVM_ENABLE_RUNTIMES REPLACE "^libcxx$" "libcxxabi" AT ${_libcxx_index})
+    list(TRANSFORM LLVM_ENABLE_RUNTIMES REPLACE "^libcxxabi$" "libcxx" AT ${_libcxxabi_index})
+  endif()
+endif()
+
 foreach(proj ${LLVM_ENABLE_RUNTIMES})
   set(proj_dir "${CMAKE_CURRENT_SOURCE_DIR}/../${proj}")
   if(IS_DIRECTORY ${proj_dir} AND EXISTS ${proj_dir}/CMakeLists.txt)