Index: include/llvm/Analysis/TargetLibraryInfo.def
===================================================================
--- include/llvm/Analysis/TargetLibraryInfo.def
+++ include/llvm/Analysis/TargetLibraryInfo.def
@@ -406,6 +406,15 @@
 /// long double floorl(long double x);
 TLI_DEFINE_ENUM_INTERNAL(floorl)
 TLI_DEFINE_STRING_INTERNAL("floorl")
+/// int fls(int i);
+TLI_DEFINE_ENUM_INTERNAL(fls)
+TLI_DEFINE_STRING_INTERNAL("fls")
+/// int flsl(long int i);
+TLI_DEFINE_ENUM_INTERNAL(flsl)
+TLI_DEFINE_STRING_INTERNAL("flsl")
+/// int flsll(long long int i);
+TLI_DEFINE_ENUM_INTERNAL(flsll)
+TLI_DEFINE_STRING_INTERNAL("flsll")
 /// double fmax(double x, double y);
 TLI_DEFINE_ENUM_INTERNAL(fmax)
 TLI_DEFINE_STRING_INTERNAL("fmax")
Index: lib/Analysis/TargetLibraryInfo.cpp
===================================================================
--- lib/Analysis/TargetLibraryInfo.cpp
+++ lib/Analysis/TargetLibraryInfo.cpp
@@ -343,6 +343,16 @@
     TLI.setUnavailable(LibFunc::ffsll);
   }
 
+  // The following functions are available on at least FreeBSD:
+  // http://svn.freebsd.org/base/head/lib/libc/string/fls.c
+  // http://svn.freebsd.org/base/head/lib/libc/string/flsl.c
+  // http://svn.freebsd.org/base/head/lib/libc/string/flsll.c
+  if (!T.isOSFreeBSD()) {
+    TLI.setUnavailable(LibFunc::fls);
+    TLI.setUnavailable(LibFunc::flsl);
+    TLI.setUnavailable(LibFunc::flsll);
+  }
+
   // The following functions are available on at least Linux:
   if (!T.isOSLinux()) {
     TLI.setUnavailable(LibFunc::dunder_strdup);