Index: llvm/trunk/test/FileCheck/check-empty2.txt
===================================================================
--- llvm/trunk/test/FileCheck/check-empty2.txt
+++ llvm/trunk/test/FileCheck/check-empty2.txt
@@ -0,0 +1,4 @@
+; Check that tool does not crash when there is no any data
+; in file after -check-prefix=PREFIX option.
+
+; RUN: not FileCheck -input-file %s %s -check-prefix=A
\ No newline at end of file
Index: llvm/trunk/utils/FileCheck/FileCheck.cpp
===================================================================
--- llvm/trunk/utils/FileCheck/FileCheck.cpp
+++ llvm/trunk/utils/FileCheck/FileCheck.cpp
@@ -718,6 +718,9 @@
 }
 
 static Check::CheckType FindCheckType(StringRef Buffer, StringRef Prefix) {
+  if (Buffer.size() <= Prefix.size())
+    return Check::CheckNone;
+
   char NextChar = Buffer[Prefix.size()];
 
   // Verify that the : is present after the prefix.