diff --git a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
--- a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
+++ b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
@@ -2165,29 +2165,40 @@
       return Error(Parser.getTok().getLoc(),
                    "unexpected token, expected identifier");
 
-    StringRef Extension = Parser.getTok().getString();
+    StringRef ExtStr = Parser.getTok().getString();
 
-    // TODO: Enable or disable extension according to extension and extension
-    // version number. Currently extension version number is not supported.
-    if (Extension.find_if(isDigit) != StringRef::npos)
+    if (ExtStr.find_if(isDigit) != StringRef::npos)
       return Error(Parser.getTok().getLoc(),
-                   "extension version number is not yet supported");
-
-    for (auto Feature : RISCVFeatureKV) {
-      if (Extension == Feature.Key) {
-        if (IsAdd) {
-          setFeatureBits(Feature.Value, Feature.Key);
-          getTargetStreamer().emitDirectiveOptionArchPlus(Extension);
-        } else {
-          clearFeatureBits(Feature.Value, Feature.Key);
-          getTargetStreamer().emitDirectiveOptionArchMinus(Extension);
-        }
-        Parser.Lex();
-        return Parser.parseToken(AsmToken::EndOfStatement,
-                                 "unexpected token, expected end of statement");
+                   "Don't specify version number, extensions don't rely on "
+                   "version numbers");
+
+    ArrayRef<SubtargetFeatureKV> KVArray(RISCVFeatureKV);
+    auto Ext = llvm::lower_bound(KVArray, ExtStr);
+    if (Ext == KVArray.end() || StringRef(Ext->Key) != ExtStr)
+      return Error(Parser.getTok().getLoc(), "unknown extension");
+
+    if (IsAdd) {
+      setFeatureBits(Ext->Value, Ext->Key);
+      getTargetStreamer().emitDirectiveOptionArchPlus(Ext->Key);
+    } else {
+      // Check dependency. It is invalid to disable an extension that
+      // there are other enabled extensions depend on it.
+      for (auto Feature : KVArray) {
+        if (getSTI().hasFeature(Feature.Value) &&
+            Feature.Implies.test(Ext->Value))
+          return Error(Parser.getTok().getLoc(),
+                       Twine("Can't disable ") + Ext->Key + " extension, " +
+                           Feature.Key + " extension requires " + Ext->Key +
+                           " extension be enabled");
       }
+
+      clearFeatureBits(Ext->Value, Ext->Key);
+      getTargetStreamer().emitDirectiveOptionArchMinus(Ext->Key);
     }
-    return Error(Parser.getTok().getLoc(), "unknown extension");
+
+    Parser.Lex();
+    return Parser.parseToken(AsmToken::EndOfStatement,
+                             "unexpected token, expected end of statement");
   }
 
   if (Option == "rvc") {
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
@@ -116,10 +116,10 @@
   OS << "\t .option\tarch,\t=" << Value << "\"\n";
 }
 void RISCVTargetAsmStreamer::emitDirectiveOptionArchPlus(StringRef Value) {
-  OS << "\t .option\tarch,\t+" << Value << "\"\n";
+  OS << "\t .option\tarch,\t+" << Value << "\n";
 }
 void RISCVTargetAsmStreamer::emitDirectiveOptionArchMinus(StringRef Value) {
-  OS << "\t .option\tarch,\t-" << Value << "\"\n";
+  OS << "\t .option\tarch,\t-" << Value << "\n";
 }
 
 void RISCVTargetAsmStreamer::finishAttributeSection() {}
diff --git a/llvm/test/MC/RISCV/option-invalid.s b/llvm/test/MC/RISCV/option-invalid.s
--- a/llvm/test/MC/RISCV/option-invalid.s
+++ b/llvm/test/MC/RISCV/option-invalid.s
@@ -25,9 +25,13 @@
 # CHECK: error: unexpected token, expected end of statement
 .option arch, +c foo
 
-# CHECK: error: extension version number is not yet supported
+# CHECK: error: Don't specify version number, extensions don't rely on version numbers
 .option arch, +c2p0
 
+.option arch, +d
+# CHECK: error: Can't disable f extension, d extension requires f extension be enabled
+.option arch, -f
+
 # CHECK: error: unexpected token, expected end of statement
 .option rvc foo
 
@@ -42,3 +46,4 @@
 
 # CHECK: error: unexpected token, expected end of statement
 .option pop 123
+