diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index ba63484d8c0a..a846eaeb2a46 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -58,13 +58,22 @@ endif( MSVC )
 option(LLVM_ENABLE_THREADS "Use threads if available." ON)
 
 if( uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE" )
-  option(LLVM_ENABLE_ASSERTS "Enable asserts" OFF)
+  option(LLVM_ENABLE_ASSERTIONS "Enable assertions" OFF)
 else()
-  option(LLVM_ENABLE_ASSERTS "Enable asserts" ON)
+  option(LLVM_ENABLE_ASSERTIONS "Enable assertions" ON)
 endif()
 
-if( LLVM_ENABLE_ASSERTS )
-  add_definitions( -D_DEBUG -UNDEBUG )
+if( LLVM_ENABLE_ASSERTIONS )
+  add_definitions( -D_DEBUG )
+  # On Release builds cmake automatically defines NDEBUG, so we
+  # explicitly undefine it:
+  if( uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE" )
+    add_definitions( -UNDEBUG )
+  endif()
+else()
+  if( NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE" )
+    add_definitions( -DNDEBUG )
+  endif()
 endif()
 
 if( LLVM_TARGETS_TO_BUILD STREQUAL "all" )
diff --git a/llvm/docs/CMake.html b/llvm/docs/CMake.html
index b329ca46d62e..ac3b57a84893 100644
--- a/llvm/docs/CMake.html
+++ b/llvm/docs/CMake.html
@@ -248,8 +248,8 @@
   <dt><b>LLVM_ENABLE_THREADS</b>:BOOL</dt>
   <dd>Build with threads support, if available. Defaults to ON.</dd>
 
-  <dt><b>LLVM_ENABLE_ASSERTS</b>:BOOL</dt>
-  <dd>Enables code asserts. Defaults to ON if and only if
+  <dt><b>LLVM_ENABLE_ASSERTIONS</b>:BOOL</dt>
+  <dd>Enables code assertions. Defaults to ON if and only if
     CMAKE_BUILD_TYPE is <i>Release</i>.</dd>
 
   <dt><b>LLVM_ENABLE_PIC</b>:BOOL</dt>