Index: lib/Format/WhitespaceManager.cpp
===================================================================
--- lib/Format/WhitespaceManager.cpp
+++ lib/Format/WhitespaceManager.cpp
@@ -679,11 +679,15 @@
   case FormatStyle::UT_Always: {
     unsigned FirstTabWidth =
         Style.TabWidth - WhitespaceStartColumn % Style.TabWidth;
-    // Indent with tabs only when there's at least one full tab.
-    if (FirstTabWidth + Style.TabWidth <= Spaces) {
-      Spaces -= FirstTabWidth;
-      Text.append("\t");
+    // Insert only spaces when we want to end up before the next tab.
+    if (Spaces < FirstTabWidth || Spaces == 1) {
+      Text.append(Spaces, ' ');
+      break;
     }
+    // Align to the next tab.
+    Spaces -= FirstTabWidth;
+    Text.append("\t");
+
     Text.append(Spaces / Style.TabWidth, '\t');
     Text.append(Spaces % Style.TabWidth, ' ');
     break;
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -8751,6 +8751,9 @@
                "\t\t    parameter2); \\\n"
                "\t}",
                Tab);
+  verifyFormat("int a;\t      // x\n"
+               "int bbbbbbbb; // x\n",
+               Tab);
 
   Tab.TabWidth = 4;
   Tab.IndentWidth = 8;