Index: lib/builtins/CMakeLists.txt
===================================================================
--- lib/builtins/CMakeLists.txt
+++ lib/builtins/CMakeLists.txt
@@ -162,6 +162,7 @@
       gcc_personality_v0.c)
 endif ()
 
+if(NOT MSVC)
 set(x86_64_SOURCES
   x86_64/floatdidf.c
   x86_64/floatdisf.c
@@ -203,6 +204,18 @@
 
 set(i686_SOURCES
   ${i386_SOURCES})
+else () # i.e. MSVC
+# Use C versions of functions when building on MSVC
+# MSVC's assembler takes Intel syntax, not AT&T syntax
+set(x86_64_SOURCES
+  x86_64/floatdidf.c
+  x86_64/floatdisf.c
+  x86_64/floatdixf.c
+  ${GENERIC_SOURCES})
+set(x86_64h_SOURCES ${x86_64_SOURCES})
+set(i386_SOURCES ${GENERIC_SOURCES})
+set(i686_SOURCES ${i386_SOURCES})
+endif () # if(NOT MSVC)
 
 set(arm_SOURCES
   arm/adddf3vfp.S