Index: lib/AsmParser/LLLexer.cpp
===================================================================
--- lib/AsmParser/LLLexer.cpp
+++ lib/AsmParser/LLLexer.cpp
@@ -937,7 +937,8 @@
     }
   }
 
-  APFloatVal = APFloat(std::atof(TokStart));
+  APFloatVal = APFloat(APFloat::IEEEdouble,
+                       StringRef(TokStart, CurPtr - TokStart));
   return lltok::APFloat;
 }
 
@@ -973,6 +974,7 @@
     }
   }
 
-  APFloatVal = APFloat(std::atof(TokStart));
+  APFloatVal = APFloat(APFloat::IEEEdouble,
+                       StringRef(TokStart, CurPtr - TokStart));
   return lltok::APFloat;
 }