diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4465,10 +4465,16 @@
   }
   case Instruction::Call: {
     auto *CI = cast<const CallInst>(Inst);
-    const Function *Callee = CI->getCalledFunction();
+
+    // The called function depends on the set of threads executing it, which
+    // could change if the call is moved to a different location in control
+    // flow.
+    if (CI->isConvergent())
+      return false;
 
     // The called function could have undefined behavior or side-effects, even
     // if marked readnone nounwind.
+    const Function *Callee = CI->getCalledFunction();
     return Callee && Callee->isSpeculatable();
   }
   case Instruction::VAArg:
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1296,6 +1296,13 @@
       isa<CallBrInst>(I1))
     return false;
 
+  // Cannot hoist convergent calls since that could change the set of threads
+  // with which they communicate.
+  if (const auto *C = dyn_cast<CallBase>(I1)) {
+    if (C->isConvergent())
+      return false;
+  }
+
   BasicBlock *BIParent = BI->getParent();
 
   bool Changed = false;
@@ -1518,14 +1525,20 @@
         I->getType()->isTokenTy())
       return false;
 
-    // Conservatively return false if I is an inline-asm instruction. Sinking
-    // and merging inline-asm instructions can potentially create arguments
-    // that cannot satisfy the inline-asm constraints.
-    // If the instruction has nomerge attribute, return false.
-    if (const auto *C = dyn_cast<CallBase>(I))
+    if (const auto *C = dyn_cast<CallBase>(I)) {
+      // Conservatively return false if I is an inline-asm instruction. Sinking
+      // and merging inline-asm instructions can potentially create arguments
+      // that cannot satisfy the inline-asm constraints.
+      // If the instruction has nomerge attribute, return false.
       if (C->isInlineAsm() || C->cannotMerge())
         return false;
 
+      // Do not sink convergent calls, as sinking may affect the set of threads
+      // with which the convergent operation communicates.
+      if (C->isConvergent())
+        return false;
+    }
+
     // Each instruction must have zero or one use.
     if (HasUse && !I->hasOneUse())
       return false;
diff --git a/llvm/test/Transforms/SimplifyCFG/attr-convergent.ll b/llvm/test/Transforms/SimplifyCFG/attr-convergent.ll
--- a/llvm/test/Transforms/SimplifyCFG/attr-convergent.ll
+++ b/llvm/test/Transforms/SimplifyCFG/attr-convergent.ll
@@ -3,6 +3,7 @@
 ; Checks that the SimplifyCFG pass won't duplicate a call to a function marked
 ; convergent.
 ;
+; CHECK-LABEL: @check
 ; CHECK: call void @barrier
 ; CHECK-NOT: call void @barrier
 define void @check(i1 %cond, i32* %out) {
@@ -25,4 +26,51 @@
   ret void
 }
 
+; CHECK-LABEL: @dont_merge_convergent
+; CHECK: if.then:
+; CHECK:   %ballot.then = call i32 @ballot
+; CHECK: if.else:
+; CHECK:   %ballot.else = call i32 @ballot
+define i32 @dont_merge_convergent(i1 %cond1, i1 %cond2) {
+entry:
+  %tok = call token @llvm.experimental.convergence.anchor()
+  br i1 %cond1, label %if.then, label %if.else
+
+if.then:
+  %ballot.then = call i32 @ballot(i1 %cond2) [ "convergencectrl"(token %tok) ]
+  br label %end
+
+if.else:
+  %ballot.else = call i32 @ballot(i1 %cond2) [ "convergencectrl"(token %tok) ]
+  br label %end
+
+end:
+  %ballot = phi i32 [ %ballot.then, %if.then ], [ %ballot.else, %if.else ]
+  ret i32 %ballot
+}
+
+; CHECK-LABEL: @dont_speculate_convergent
+; CHECK: entry:
+; CHECK: then:
+; CHECK:   call i32 @speculatable_convergent
+; CHECK: end:
+define i32 @dont_speculate_convergent(i1 %cond1, i32 %in) {
+entry:
+  %tok = call token @llvm.experimental.convergence.anchor()
+  br i1 %cond1, label %then, label %end
+
+then:
+  %v = call i32 @speculatable_convergent(i32 %in) [ "convergencectrl"(token %tok) ]
+  br label %end
+
+end:
+  %r = phi i32 [ 0, %entry ], [ %v, %then ]
+  ret i32 %r
+}
+
+declare token @llvm.experimental.convergence.anchor()
+
+declare i32 @ballot(i1 %arg) convergent readnone
+declare i32 @speculatable_convergent(i32) convergent readnone speculatable
+
 declare void @barrier() convergent