diff --git a/llvm/docs/HowToUseAttributes.rst b/llvm/docs/HowToUseAttributes.rst
--- a/llvm/docs/HowToUseAttributes.rst
+++ b/llvm/docs/HowToUseAttributes.rst
@@ -57,7 +57,7 @@
 
 Note: It is advised that you do *not* use the ``AttributeList`` "introspection"
 methods (e.g. ``Raw``, ``getRawPointer``, etc.).  These methods break
-encapsulation, and may be removed in a future release (i.e. LLVM 4.0).
+encapsulation, and may be removed in a future release.
 
 ``AttrBuilder``
 ===============
@@ -73,7 +73,7 @@
 
 Note: It is advised that you do *not* use the ``AttrBuilder::addRawValue()``
 method or the ``AttrBuilder(uint64_t Val)`` constructor.  These are for
-backwards compatibility and may be removed in a future release (i.e. LLVM 4.0).
+backwards compatibility and may be removed in a future release.
 
 And that's basically it! A lot of functionality is hidden behind these classes,
 but the interfaces are pretty straight forward.
diff --git a/llvm/include/llvm/Bitcode/LLVMBitCodes.h b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
--- a/llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -85,7 +85,7 @@
   MODULE_CODE_ASM = 4,         // ASM:         [strchr x N]
   MODULE_CODE_SECTIONNAME = 5, // SECTIONNAME: [strchr x N]
 
-  // FIXME: Remove DEPLIB in 4.0.
+  // Deprecated, but still needed to read old bitcode files.
   MODULE_CODE_DEPLIB = 6, // DEPLIB:      [strchr x N]
 
   // GLOBALVAR: [pointer type, isconst, initid,
@@ -121,7 +121,7 @@
 
 /// PARAMATTR blocks have code for defining a parameter attribute set.
 enum AttributeCodes {
-  // FIXME: Remove `PARAMATTR_CODE_ENTRY_OLD' in 4.0
+  // Deprecated, but still needed to read old bitcode files.
   PARAMATTR_CODE_ENTRY_OLD = 1, // ENTRY: [paramidx0, attr0,
                                 //         paramidx1, attr1...]
   PARAMATTR_CODE_ENTRY = 2,     // ENTRY: [attrgrp0, attrgrp1, ...]
diff --git a/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp b/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp
@@ -130,7 +130,7 @@
       STRINGIFY_CODE(MODULE_CODE, DATALAYOUT)
       STRINGIFY_CODE(MODULE_CODE, ASM)
       STRINGIFY_CODE(MODULE_CODE, SECTIONNAME)
-      STRINGIFY_CODE(MODULE_CODE, DEPLIB) // FIXME: Remove in 4.0
+      STRINGIFY_CODE(MODULE_CODE, DEPLIB) // Deprecated, present in old bitcode
       STRINGIFY_CODE(MODULE_CODE, GLOBALVAR)
       STRINGIFY_CODE(MODULE_CODE, FUNCTION)
       STRINGIFY_CODE(MODULE_CODE, ALIAS)
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1317,8 +1317,6 @@
 /// 'encodeLLVMAttributesForBitcode'.
 static void decodeLLVMAttributesForBitcode(AttrBuilder &B,
                                            uint64_t EncodedAttrs) {
-  // FIXME: Remove in 4.0.
-
   // The alignment is stored as a 16-bit raw value from bits 31--16.  We shift
   // the bits above 31 down by 11 bits.
   unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
@@ -1369,7 +1367,7 @@
     default:  // Default behavior: ignore.
       break;
     case bitc::PARAMATTR_CODE_ENTRY_OLD: // ENTRY: [paramidx0, attr0, ...]
-      // FIXME: Remove in 4.0.
+      // Deprecated, but still needed to read old bitcode files.
       if (Record.size() & 1)
         return error("Invalid record");
 
@@ -1777,7 +1775,7 @@
       break;
     }
     case bitc::TYPE_CODE_FUNCTION_OLD: {
-      // FIXME: attrid is dead, remove it in LLVM 4.0
+      // Deprecated, but still needed to read old bitcode files.
       // FUNCTION: [vararg, attrid, retty, paramty x N]
       if (Record.size() < 3)
         return error("Invalid record");
@@ -2702,8 +2700,10 @@
         if (!IdxTy)
           return error("Invalid record");
         Op1 = ValueList.getConstantFwdRef(Record[3], IdxTy);
-      } else // TODO: Remove with llvm 4.0
+      } else {
+        // Deprecated, but still needed to read old bitcode files.
         Op1 = ValueList.getConstantFwdRef(Record[2], Type::getInt32Ty(Context));
+      }
       if (!Op1)
         return error("Invalid record");
       V = ConstantExpr::getExtractElement(Op0, Op1);
@@ -2723,8 +2723,10 @@
         if (!IdxTy)
           return error("Invalid record");
         Op2 = ValueList.getConstantFwdRef(Record[3], IdxTy);
-      } else // TODO: Remove with llvm 4.0
+      } else {
+        // Deprecated, but still needed to read old bitcode files.
         Op2 = ValueList.getConstantFwdRef(Record[2], Type::getInt32Ty(Context));
+      }
       if (!Op2)
         return error("Invalid record");
       V = ConstantExpr::getInsertElement(Op0, Op1, Op2);
@@ -2766,7 +2768,7 @@
       break;
     }
     // This maintains backward compatibility, pre-asm dialect keywords.
-    // FIXME: Remove with the 4.0 release.
+    // Deprecated, but still needed to read old bitcode files.
     case bitc::CST_CODE_INLINEASM_OLD: {
       if (Record.size() < 2)
         return error("Invalid record");
@@ -3167,8 +3169,8 @@
   }
   GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
   // Local linkage must have default visibility.
+  // auto-upgrade `hidden` and `protected` for old bitcode.
   if (Record.size() > 6 && !GlobalValue::isLocalLinkage(Linkage))
-    // FIXME: Change to an error if non-default in 4.0.
     Visibility = getDecodedVisibility(Record[6]);
 
   GlobalVariable::ThreadLocalMode TLM = GlobalVariable::NotThreadLocal;
@@ -3297,8 +3299,8 @@
     Func->setSection(SectionTable[Record[6] - 1]);
   }
   // Local linkage must have default visibility.
+  // auto-upgrade `hidden` and `protected` for old bitcode.
   if (!Func->hasLocalLinkage())
-    // FIXME: Change to an error if non-default in 4.0.
     Func->setVisibility(getDecodedVisibility(Record[7]));
   if (Record.size() > 8 && Record[8]) {
     if (Record[8] - 1 >= GCTable.size())
@@ -3405,12 +3407,11 @@
 
   assert(NewGA->getValueType() == flattenPointerTypes(FullTy) &&
          "Incorrect fully structured type provided for GlobalIndirectSymbol");
-  // Old bitcode files didn't have visibility field.
   // Local linkage must have default visibility.
+  // auto-upgrade `hidden` and `protected` for old bitcode.
   if (OpNum != Record.size()) {
     auto VisInd = OpNum++;
     if (!NewGA->hasLocalLinkage())
-      // FIXME: Change to an error if non-default in 4.0.
       NewGA->setVisibility(getDecodedVisibility(Record[VisInd]));
   }
   if (BitCode == bitc::MODULE_CODE_ALIAS ||
@@ -3663,7 +3664,7 @@
       break;
     }
     case bitc::MODULE_CODE_DEPLIB: {  // DEPLIB: [strchr x N]
-      // FIXME: Remove in 4.0.
+      // Deprecated, but still needed to read old bitcode files.
       std::string S;
       if (convertToString(Record, 0, S))
         return error("Invalid record");
diff --git a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
--- a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
+++ b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
@@ -1132,7 +1132,7 @@
     break;
   }
   case bitc::METADATA_OLD_FN_NODE: {
-    // FIXME: Remove in 4.0.
+    // Deprecated, but still needed to read old bitcode files.
     // This is a LocalAsMetadata record, the only type of function-local
     // metadata.
     if (Record.size() % 2 == 1)
@@ -1162,7 +1162,7 @@
     break;
   }
   case bitc::METADATA_OLD_NODE: {
-    // FIXME: Remove in 4.0.
+    // Deprecated, but still needed to read old bitcode files.
     if (Record.size() % 2 == 1)
       return error("Invalid record");
 
diff --git a/llvm/lib/IR/DataLayout.cpp b/llvm/lib/IR/DataLayout.cpp
--- a/llvm/lib/IR/DataLayout.cpp
+++ b/llvm/lib/IR/DataLayout.cpp
@@ -261,7 +261,6 @@
     switch (Specifier) {
     case 's':
       // Ignored for backward compatibility.
-      // FIXME: remove this on LLVM 4.0.
       break;
     case 'E':
       BigEndian = true;