diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -190,6 +190,9 @@
     ProgramStateRef apply(ProgramStateRef State, const CallEvent &Call,
                           const Summary &Summary) const override {
       SVal V = getArgSVal(Call, getArgNo());
+      if (V.isUndef())
+        return State;
+
       DefinedOrUnknownSVal L = V.castAs<DefinedOrUnknownSVal>();
       if (!L.getAs<Loc>())
         return State;
diff --git a/clang/test/Analysis/std-c-library-functions.c b/clang/test/Analysis/std-c-library-functions.c
--- a/clang/test/Analysis/std-c-library-functions.c
+++ b/clang/test/Analysis/std-c-library-functions.c
@@ -89,6 +89,14 @@
   clang_analyzer_eval(z <= y); // expected-warning{{TRUE}}
 }
 
+void test_fread_uninitialized(void) {
+  void *ptr;
+  size_t sz;
+  size_t nmem;
+  FILE *fp;
+  (void)fread(ptr, sz, nmem, fp); // expected-warning {{1st function call argument is an uninitialized value}}
+}
+
 ssize_t getline(char **, size_t *, FILE *);
 void test_getline(FILE *fp) {
   char *line = 0;