diff --git a/llvm/lib/ProfileData/SampleProfReader.cpp b/llvm/lib/ProfileData/SampleProfReader.cpp
--- a/llvm/lib/ProfileData/SampleProfReader.cpp
+++ b/llvm/lib/ProfileData/SampleProfReader.cpp
@@ -328,7 +328,8 @@
   ProfileIsFS = ProfileIsFSDisciminator;
   FunctionSamples::ProfileIsFS = ProfileIsFS;
   for (; !LineIt.is_at_eof(); ++LineIt) {
-    if ((*LineIt)[(*LineIt).find_first_not_of(' ')] == '#')
+    size_t pos = LineIt->find_first_not_of(' ');
+    if (pos == LineIt->npos || (*LineIt)[pos] == '#')
       continue;
     // Read the header of each function.
     //
diff --git a/llvm/test/tools/llvm-profdata/Inputs/sample-empty-lines.proftext b/llvm/test/tools/llvm-profdata/Inputs/sample-empty-lines.proftext
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-profdata/Inputs/sample-empty-lines.proftext
@@ -0,0 +1,9 @@
+main:10:1
+ 2: 3
+ 
+
+ 3: inline1:5
+  
+  4: 1
+ 
+
diff --git a/llvm/test/tools/llvm-profdata/sample-empty-lines.test b/llvm/test/tools/llvm-profdata/sample-empty-lines.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-profdata/sample-empty-lines.test
@@ -0,0 +1,8 @@
+Test llvm-profdata merge can handle empty line with spaces in text format sample profile.
+
+RUN: llvm-profdata merge --sample --text %p/Inputs/sample-empty-lines.proftext | FileCheck %s
+CHECK: main:10:1
+CHECK-NEXT: 2: 3
+CHECK-NEXT: 3: inline1:5
+CHECK-NEXT: 4: 1
+