diff --git a/lldb/include/lldb/Core/DebuggerEvents.h b/lldb/include/lldb/Core/DebuggerEvents.h
--- a/lldb/include/lldb/Core/DebuggerEvents.h
+++ b/lldb/include/lldb/Core/DebuggerEvents.h
@@ -32,6 +32,7 @@
 
   static const ProgressEventData *GetEventDataFromEvent(const Event *event_ptr);
   uint64_t GetID() const { return m_id; }
+  bool IsFinite() const { return m_total != UINT64_MAX; }
   uint64_t GetCompleted() const { return m_completed; }
   uint64_t GetTotal() const { return m_total; }
   const std::string &GetMessage() const { return m_message; }
diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -1857,11 +1857,26 @@
     output->Printf(
         "%s", ansi::FormatAnsiTerminalCodes(ansi_prefix, use_color).c_str());
 
-  // Print the progress message.
+  // Trim the progress message if it exceeds the window's width and print it.
   std::string message = data->GetMessage();
-  if (data->GetTotal() != UINT64_MAX) {
+  uint64_t progress_total = data->GetTotal();
+  uint32_t term_width = GetTerminalWidth();
+
+  size_t prefix_width = 0;
+  if (data->IsFinite()) {
+    prefix_width += 4; // '[%PRIu64/%PRIu64] %s'
+    prefix_width += std::to_string(progress_total).size() * 2;
+  }
+
+  const size_t suffix_width = 3; // %s...
+
+  if (message.size() + prefix_width + suffix_width >= term_width)
+    message.erase(message.begin() + term_width - prefix_width - suffix_width,
+                  message.end());
+
+  if (data->IsFinite()) {
     output->Printf("[%" PRIu64 "/%" PRIu64 "] %s...", data->GetCompleted(),
-                   data->GetTotal(), message.c_str());
+                   progress_total, message.c_str());
   } else {
     output->Printf("%s...", message.c_str());
   }