diff --git a/lib/IR/GCOV.cpp b/lib/IR/GCOV.cpp
index dc9cb4b2a81..f69bdc4f8cc 100644
--- a/lib/IR/GCOV.cpp
+++ b/lib/IR/GCOV.cpp
@@ -308,6 +308,11 @@ void GCOVFunction::dump() const {
 /// collectLineCounts - Collect line counts. This must be used after
 /// reading .gcno and .gcda files.
 void GCOVFunction::collectLineCounts(FileInfo &FI) {
+  // If the line number is zero, this is a function that doesn't actually appear
+  // in the source file, so there isn't anything we can do with it.
+  if (LineNumber == 0)
+    return;
+
   for (SmallVectorImpl<GCOVBlock *>::iterator I = Blocks.begin(),
          E = Blocks.end(); I != E; ++I)
     (*I)->collectLineCounts(FI);
diff --git a/test/tools/llvm-cov/Inputs/copy_block_helper.gcda b/test/tools/llvm-cov/Inputs/copy_block_helper.gcda
new file mode 100644
index 00000000000..d7ff4696df7
Binary files /dev/null and b/test/tools/llvm-cov/Inputs/copy_block_helper.gcda differ
diff --git a/test/tools/llvm-cov/Inputs/copy_block_helper.gcno b/test/tools/llvm-cov/Inputs/copy_block_helper.gcno
new file mode 100644
index 00000000000..a9d10840646
Binary files /dev/null and b/test/tools/llvm-cov/Inputs/copy_block_helper.gcno differ
diff --git a/test/tools/llvm-cov/copy_block_helper.m b/test/tools/llvm-cov/copy_block_helper.m
new file mode 100644
index 00000000000..61a91c1e77e
--- /dev/null
+++ b/test/tools/llvm-cov/copy_block_helper.m
@@ -0,0 +1,29 @@
+// Make sure that compiler-added functions (whose line number is zero) don't
+// crash llvm-cov.
+
+// We need shell for cd
+// REQUIRES: shell
+
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: cd %t
+// RUN: cp %s %p/Inputs/copy_block_helper.gc* .
+
+// RUN: llvm-cov copy_block_helper.m | FileCheck %s --check-prefix=STDOUT
+// STDOUT: File 'copy_block_helper.m'
+// STDOUT: Lines executed:100.00% of 5
+// STDOUT: copy_block_helper.m:creating 'copy_block_helper.m.gcov'
+
+// RUN: FileCheck %s --check-prefix=GCOV < %t/copy_block_helper.m.gcov
+// GCOV: -:    0:Runs:1
+// GCOV: -:    0:Programs:1
+
+id test_helper(id (^foo)(void)) { return foo(); } // GCOV: 1:    [[@LINE]]:id
+void test(id x) { // GCOV: -:    [[@LINE]]:void test
+  test_helper(^{  // GCOV: 2:    [[@LINE]]:  test_helper
+    return x;     // GCOV: 1:    [[@LINE]]:    return
+  });             // GCOV: -:    [[@LINE]]:
+}                 // GCOV: 1:    [[@LINE]]:}
+
+// GCOV: 1:    [[@LINE+1]]:int main
+int main(int argc, const char *argv[]) { test(0); }
diff --git a/test/tools/llvm-cov/lit.local.cfg b/test/tools/llvm-cov/lit.local.cfg
index df9b335dd13..f738810475f 100644
--- a/test/tools/llvm-cov/lit.local.cfg
+++ b/test/tools/llvm-cov/lit.local.cfg
@@ -1 +1 @@
-config.suffixes = ['.test']
+config.suffixes = ['.test', '.m']