Index: lldb/source/Core/IOHandlerCursesGUI.cpp
===================================================================
--- lldb/source/Core/IOHandlerCursesGUI.cpp
+++ lldb/source/Core/IOHandlerCursesGUI.cpp
@@ -362,23 +362,23 @@
   }
   void Clear() { ::wclear(m_window); }
   void Erase() { ::werase(m_window); }
-  Rect GetBounds() {
+  Rect GetBounds() const {
     return Rect(GetParentOrigin(), GetSize());
   } // Get the rectangle in our parent window
   int GetChar() { return ::wgetch(m_window); }
-  int GetCursorX() { return getcurx(m_window); }
-  int GetCursorY() { return getcury(m_window); }
-  Rect GetFrame() {
+  int GetCursorX() const { return getcurx(m_window); }
+  int GetCursorY() const { return getcury(m_window); }
+  Rect GetFrame() const {
     return Rect(Point(), GetSize());
   } // Get our rectangle in our own coordinate system
-  Point GetParentOrigin() { return Point(GetParentX(), GetParentY()); }
-  Size GetSize() { return Size(GetWidth(), GetHeight()); }
-  int GetParentX() { return getparx(m_window); }
-  int GetParentY() { return getpary(m_window); }
-  int GetMaxX() { return getmaxx(m_window); }
-  int GetMaxY() { return getmaxy(m_window); }
-  int GetWidth() { return GetMaxX(); }
-  int GetHeight() { return GetMaxY(); }
+  Point GetParentOrigin() const { return Point(GetParentX(), GetParentY()); }
+  Size GetSize() const { return Size(GetWidth(), GetHeight()); }
+  int GetParentX() const { return getparx(m_window); }
+  int GetParentY() const { return getpary(m_window); }
+  int GetMaxX() const { return getmaxx(m_window); }
+  int GetMaxY() const { return getmaxy(m_window); }
+  int GetWidth() const { return GetMaxX(); }
+  int GetHeight() const { return GetMaxY(); }
   void MoveCursor(int x, int y) { ::wmove(m_window, y, x); }
   void MoveWindow(int x, int y) { MoveWindow(Point(x, y)); }
   void Resize(int w, int h) { ::wresize(m_window, h, w); }
@@ -391,7 +391,7 @@
     ::wbkgd(m_window, COLOR_PAIR(color_pair_idx));
   }
 
-  void PutCStringTruncated(const char *s, int right_pad) {
+  void PutCStringTruncated(int right_pad, const char *s) {
     int bytes_left = GetWidth() - GetCursorX();
     if (bytes_left > right_pad) {
       bytes_left -= right_pad;
@@ -433,6 +433,28 @@
     va_end(args);
   }
 
+  void PrintfTruncated(int right_pad, const char *format, ...)
+      __attribute__((format(printf, 3, 4))) {
+    va_list args;
+    va_start(args, format);
+    int size = vsnprintf(nullptr, 0, format, args);
+    va_end(args);
+    if (size <= 0)
+      return;
+    ++size; // for \0
+    std::vector<char> buffer(size);
+    va_start(args, format);
+    size = vsnprintf(buffer.data(), size, format, args);
+    va_end(args);
+    if (size <= 0)
+      return;
+    PutCStringTruncated(right_pad, buffer.data());
+  }
+
+  size_t LimitLengthToRestOfLine(size_t length) const {
+    return std::min<size_t>(length, std::max(0, GetWidth() - GetCursorX() - 1));
+  }
+
   void Touch() {
     ::touchwin(m_window);
     if (m_parent)
@@ -548,7 +570,7 @@
       } else {
         MoveCursor(1, GetHeight() - 1);
         PutChar('[');
-        PutCStringTruncated(bottom_message, 1);
+        PutCStringTruncated(1, bottom_message);
       }
     }
     if (attr)
@@ -1910,7 +1932,7 @@
         if (FormatEntity::Format(m_format, strm, &sc, &exe_ctx, nullptr,
                                  nullptr, false, false)) {
           int right_pad = 1;
-          window.PutCStringTruncated(strm.GetString().str().c_str(), right_pad);
+          window.PutCStringTruncated(right_pad, strm.GetString().str().c_str());
         }
       }
     }
@@ -1969,7 +1991,7 @@
       if (FormatEntity::Format(m_format, strm, nullptr, &exe_ctx, nullptr,
                                nullptr, false, false)) {
         int right_pad = 1;
-        window.PutCStringTruncated(strm.GetString().str().c_str(), right_pad);
+        window.PutCStringTruncated(right_pad, strm.GetString().str().c_str());
       }
     }
   }
@@ -2059,7 +2081,7 @@
       if (FormatEntity::Format(m_format, strm, nullptr, &exe_ctx, nullptr,
                                nullptr, false, false)) {
         int right_pad = 1;
-        window.PutCStringTruncated(strm.GetString().str().c_str(), right_pad);
+        window.PutCStringTruncated(right_pad, strm.GetString().str().c_str());
       }
     }
   }
@@ -2362,29 +2384,29 @@
       window.AttributeOn(A_REVERSE);
 
     if (type_name && type_name[0])
-      window.Printf("(%s) ", type_name);
+      window.PrintfTruncated(1, "(%s) ", type_name);
 
     if (name && name[0])
-      window.PutCString(name);
+      window.PutCStringTruncated(1, name);
 
     attr_t changd_attr = 0;
     if (valobj->GetValueDidChange())
       changd_attr = COLOR_PAIR(5) | A_BOLD;
 
     if (value && value[0]) {
-      window.PutCString(" = ");
+      window.PutCStringTruncated(1, " = ");
       if (changd_attr)
         window.AttributeOn(changd_attr);
-      window.PutCString(value);
+      window.PutCStringTruncated(1, value);
       if (changd_attr)
         window.AttributeOff(changd_attr);
     }
 
     if (summary && summary[0]) {
-      window.PutChar(' ');
+      window.PutCStringTruncated(1, " ");
       if (changd_attr)
         window.AttributeOn(changd_attr);
-      window.PutCString(summary);
+      window.PutCStringTruncated(1, summary);
       if (changd_attr)
         window.AttributeOff(changd_attr);
     }
@@ -2822,7 +2844,7 @@
   while (y <= max_y) {
     window.MoveCursor(x, y);
     window.PutCStringTruncated(
-        m_text.GetStringAtIndex(m_first_visible_line + y - min_y), 1);
+        1, m_text.GetStringAtIndex(m_first_visible_line + y - min_y));
     ++y;
   }
   return true;
@@ -3250,7 +3272,7 @@
         if (thread && FormatEntity::Format(m_format, strm, nullptr, &exe_ctx,
                                            nullptr, nullptr, false, false)) {
           window.MoveCursor(40, 0);
-          window.PutCStringTruncated(strm.GetString().str().c_str(), 1);
+          window.PutCStringTruncated(1, strm.GetString().str().c_str());
         }
 
         window.MoveCursor(60, 0);
@@ -3476,7 +3498,7 @@
       window.AttributeOn(A_REVERSE);
       window.MoveCursor(1, 1);
       window.PutChar(' ');
-      window.PutCStringTruncated(m_title.GetString().str().c_str(), 1);
+      window.PutCStringTruncated(1, m_title.GetString().str().c_str());
       int x = window.GetCursorX();
       if (x < window_width - 1) {
         window.Printf("%*s", window_width - x - 1, "");
@@ -3548,8 +3570,8 @@
 
           if (highlight_attr)
             window.AttributeOn(highlight_attr);
-          const uint32_t line_len =
-              m_file_sp->GetLineLength(curr_line + 1, false);
+          const uint32_t line_len = window.LimitLengthToRestOfLine(
+              m_file_sp->GetLineLength(curr_line + 1, false));
           if (line_len > 0)
             window.PutCString(m_file_sp->PeekLineData(curr_line + 1), line_len);
 
@@ -3698,7 +3720,7 @@
             strm.Printf("%s", mnemonic);
 
           int right_pad = 1;
-          window.PutCStringTruncated(strm.GetData(), right_pad);
+          window.PutCStringTruncated(right_pad, strm.GetData());
 
           if (is_pc_line && frame_sp &&
               frame_sp->GetConcreteFrameIndex() == 0) {
Index: lldb/test/API/commands/gui/viewlarge/Makefile
===================================================================
--- /dev/null
+++ lldb/test/API/commands/gui/viewlarge/Makefile
@@ -0,0 +1,2 @@
+C_SOURCES := main.c
+include Makefile.rules
Index: lldb/test/API/commands/gui/viewlarge/TestGuiViewLarge.py
===================================================================
--- /dev/null
+++ lldb/test/API/commands/gui/viewlarge/TestGuiViewLarge.py
@@ -0,0 +1,50 @@
+"""
+Test that the 'gui' displays long lines/names correctly without overruns.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.lldbpexpect import PExpectTest
+
+class GuiViewLargeCommandTest(PExpectTest):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    # PExpect uses many timeouts internally and doesn't play well
+    # under ASAN on a loaded machine..
+    @skipIfAsan
+    @skipIfCursesSupportMissing
+    @skipIfRemote # "run" command will not work correctly for remote debug
+    def test_gui(self):
+        self.build()
+
+        # Limit columns to 80, so that long lines will not be displayed completely.
+        self.launch(executable=self.getBuildArtifact("a.out"), dimensions=(100,80))
+        self.expect('br set -f main.c -p "// Break here"', substrs=["Breakpoint 1", "address ="])
+        self.expect("run", substrs=["stop reason ="])
+
+        escape_key = chr(27).encode()
+
+        # Start the GUI and close the welcome window.
+        self.child.sendline("gui")
+        self.child.send(escape_key)
+
+        # Check the sources window.
+        self.child.expect_exact("Sources")
+        # The string is copy&pasted from a 80-columns terminal. It will be followed by some
+        # kind of an escape sequence (color, frame, etc.).
+        self.child.expect_exact("int a_variable_with_a_very_looooooooooooooooooooooooooo"+chr(27))
+        # The escape here checks that there's no content drawn by the previous line.
+        self.child.expect_exact("int shortvar = 1;"+chr(27))
+
+        # Check the variable window.
+        self.child.expect_exact("Variables")
+        self.child.expect_exact("(int) a_variable_with_a_very_looooooooooooooooooooooooooooooo"+chr(27))
+        self.child.expect_exact("(int) shortvar = 1"+chr(27))
+
+        # Press escape to quit the gui
+        self.child.send(escape_key)
+
+        self.expect_prompt()
+        self.quit()
Index: lldb/test/API/commands/gui/viewlarge/main.c
===================================================================
--- /dev/null
+++ lldb/test/API/commands/gui/viewlarge/main.c
@@ -0,0 +1,7 @@
+int main(int argc, char **argv) {
+  // This is to be viewed in a 80-column terminal, so make the line below more
+  // than 120 characters wide, to span at least two lines.
+  int a_variable_with_a_very_loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong_name = 22;
+  int shortvar = 1;
+  return 0; // Break here
+}