diff --git a/lldb/source/Host/common/Editline.cpp b/lldb/source/Host/common/Editline.cpp
--- a/lldb/source/Host/common/Editline.cpp
+++ b/lldb/source/Host/common/Editline.cpp
@@ -153,6 +153,11 @@
     result.push_back(input.substr(start, end - start));
     start = end + 1;
   }
+  // Treat an empty history session as a single command of zero-length instead
+  // of returning an empty vector.
+  if (result.empty()) {
+    result.emplace_back();
+  }
   return result;
 }
 
diff --git a/lldb/test/API/commands/expression/multiline-navigation/TestMultilineNavigation.py b/lldb/test/API/commands/expression/multiline-navigation/TestMultilineNavigation.py
--- a/lldb/test/API/commands/expression/multiline-navigation/TestMultilineNavigation.py
+++ b/lldb/test/API/commands/expression/multiline-navigation/TestMultilineNavigation.py
@@ -69,3 +69,26 @@
         self.child.expect_exact("(int) $0 = 334")
 
         self.quit()
+
+    @skipIfAsan
+    @skipIfEditlineSupportMissing
+    @expectedFailureAll(oslist=['freebsd'], bugnumber='llvm.org/pr48316')
+    def test_nav_arrow_up_empty_pr49845(self):
+        """Tests that navigating with the up arrow doesn't crash."""
+        self.launch()
+
+        # Create an empty history session by only entering a newline.
+        self.child.sendline("expr")
+        self.child.expect_exact("terminate with an empty line to evaluate")
+        self.child.send("\n")
+        self.expect_prompt()
+
+        # Send just the up arrow in the expression evaluator. This should bring up the previous empty expression.
+        self.child.sendline("expr")
+        self.child.expect_exact("terminate with an empty line to evaluate")
+        self.child.send(self.arrow_up)
+        self.child.expect_exact("1: ")
+        self.child.send("\n")
+        self.expect_prompt()
+
+        self.quit()