Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -2,11 +2,6 @@
 
 cmake_minimum_required(VERSION 2.8.12.2)
 
-if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
-  message(STATUS "No build type selected, default to Debug")
-  set(CMAKE_BUILD_TYPE "Debug")
-endif()
-
 if(POLICY CMP0022)
   cmake_policy(SET CMP0022 NEW) # automatic when 2.8.12 is required
 endif()
@@ -56,6 +51,12 @@
   ${cmake_3_0_LANGUAGES}
   C CXX ASM)
 
+# PR26666: project() resets CMAKE_BUILD_TYPE so we must set it afterward:
+if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+  message(STATUS "No build type selected, default to Debug")
+  set(CMAKE_BUILD_TYPE "Debug")
+endif()
+
 # The following only works with the Ninja generator in CMake >= 3.0.
 set(LLVM_PARALLEL_COMPILE_JOBS "" CACHE STRING
   "Define the maximum number of concurrent compilation jobs.")